diff --git a/README.md b/README.md index e3c3bfa..7b30636 100644 --- a/README.md +++ b/README.md @@ -550,6 +550,19 @@ Highly experimental personal projects. * [Fermat pseudoprimes of the form p*((p-1)*n + 1)](./oeis-research/Daniel%20Suteu/Fermat%20pseudoprimes%20of%20the%20form%20p*((p-1)*n%20+%201)) * [prog.pl](./oeis-research/Daniel%20Suteu/Fermat%20pseudoprimes%20of%20the%20form%20p*((p-1)*n%20+%201)/prog.pl) * [prog.sf](./oeis-research/Daniel%20Suteu/Fermat%20pseudoprimes%20of%20the%20form%20p*((p-1)*n%20+%201)/prog.sf) + * [First number k such that k + a(i) has n distinct prime factors, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20k%20+%20a(i)%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20k%20+%20a(i)%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n/prog.sf) + * [First number k such that k + a(i) is the product of n distinct prime factors, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20k%20+%20a(i)%20is%20the%20product%20of%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n) + * [prog.pl](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20k%20+%20a(i)%20is%20the%20product%20of%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n/prog.pl) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20k%20+%20a(i)%20is%20the%20product%20of%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n/prog.sf) + * [First number k such that the concatenation of a(i) and k has n distinct prime factors, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20a(i)%20and%20k%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20a(i)%20and%20k%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n/prog.sf) + * [First number k such that the concatenation of a(i) and k has n prime factors, counted with multiplicity, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20a(i)%20and%20k%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20a(i)%20and%20k%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n/prog.sf) + * [First number k such that the concatenation of k and a(i) has n distinct prime factors, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20k%20and%20a(i)%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20k%20and%20a(i)%20has%20n%20distinct%20prime%20factors,%20for%20all%20i%20<%20n/prog.sf) + * [First number k such that the concatenation of k and a(i) has n prime factors, counted with multiplicity, for all i < n](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20k%20and%20a(i)%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n) + * [prog.sf](./oeis-research/Daniel%20Suteu/First%20number%20k%20such%20that%20the%20concatenation%20of%20k%20and%20a(i)%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n/prog.sf) * [Generalized class of primes](./oeis-research/Daniel%20Suteu/Generalized%20class%20of%20primes) * [prog.sf](./oeis-research/Daniel%20Suteu/Generalized%20class%20of%20primes/prog.sf) * [Incrementally largest numbers n that are the product of primes p such that p+1 divides n](./oeis-research/Daniel%20Suteu/Incrementally%20largest%20numbers%20n%20that%20are%20the%20product%20of%20primes%20p%20such%20that%20p+1%20divides%20n) @@ -1080,6 +1093,8 @@ Highly experimental personal projects. * [is squarefree omega prime.sf](./oeis-research/J.W.L.%20(Jan)%20Eerland/Least%20prime%20p%20such%20that%20p^n%20+%204%20is%20the%20product%20of%20n%20distinct%20primes/is_squarefree_omega_prime.sf) * [Least prime p such that p^n + 6 is the product of n distinct primes](./oeis-research/J.W.L.%20(Jan)%20Eerland/Least%20prime%20p%20such%20that%20p^n%20+%206%20is%20the%20product%20of%20n%20distinct%20primes) * [is squarefree almost prime.sf](./oeis-research/J.W.L.%20(Jan)%20Eerland/Least%20prime%20p%20such%20that%20p^n%20+%206%20is%20the%20product%20of%20n%20distinct%20primes/is_squarefree_almost_prime.sf) + * [Smallest k such that 3^(4*3^n) - k is a safe prime](./oeis-research/J.W.L.%20(Jan)%20Eerland/Smallest%20k%20such%20that%203^(4*3^n)%20-%20k%20is%20a%20safe%20prime) + * [prog.sf](./oeis-research/J.W.L.%20(Jan)%20Eerland/Smallest%20k%20such%20that%203^(4*3^n)%20-%20k%20is%20a%20safe%20prime/prog.sf) * [Jacques Tramu](./oeis-research/Jacques%20Tramu) * [First odd prime in the (n-th)-order Fibonacci sequence Fn](./oeis-research/Jacques%20Tramu/First%20odd%20prime%20in%20the%20(n-th)-order%20Fibonacci%20sequence%20Fn) * [prog.pl](./oeis-research/Jacques%20Tramu/First%20odd%20prime%20in%20the%20(n-th)-order%20Fibonacci%20sequence%20Fn/prog.pl) @@ -1643,6 +1658,9 @@ Highly experimental personal projects. * [First k such that if x(1) = k and x(i+1) = A062028(x(i)), x(1) to x(n) are all semiprimes but x(n+1) is not](./oeis-research/Robert%20Israel/First%20k%20such%20that%20if%20x(1)%20=%20k%20and%20x(i+1)%20=%20A062028(x(i)),%20x(1)%20to%20x(n)%20are%20all%20semiprimes%20but%20x(n+1)%20is%20not) * [prog.pl](./oeis-research/Robert%20Israel/First%20k%20such%20that%20if%20x(1)%20=%20k%20and%20x(i+1)%20=%20A062028(x(i)),%20x(1)%20to%20x(n)%20are%20all%20semiprimes%20but%20x(n+1)%20is%20not/prog.pl) * [prog 2.pl](./oeis-research/Robert%20Israel/First%20k%20such%20that%20if%20x(1)%20=%20k%20and%20x(i+1)%20=%20A062028(x(i)),%20x(1)%20to%20x(n)%20are%20all%20semiprimes%20but%20x(n+1)%20is%20not/prog_2.pl) + * [First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n](./oeis-research/Robert%20Israel/First%20number%20k%20such%20that%20k%20+%20a(i)%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n) + * [prog.pl](./oeis-research/Robert%20Israel/First%20number%20k%20such%20that%20k%20+%20a(i)%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n/prog.pl) + * [upperbounds.pl](./oeis-research/Robert%20Israel/First%20number%20k%20such%20that%20k%20+%20a(i)%20has%20n%20prime%20factors,%20counted%20with%20multiplicity,%20for%20all%20i%20<%20n/upperbounds.pl) * [First number that is the sum of k successive semiprimes for 1 <= k <= n](./oeis-research/Robert%20Israel/First%20number%20that%20is%20the%20sum%20of%20k%20successive%20semiprimes%20for%201%20<=%20k%20<=%20n) * [prog.pl](./oeis-research/Robert%20Israel/First%20number%20that%20is%20the%20sum%20of%20k%20successive%20semiprimes%20for%201%20<=%20k%20<=%20n/prog.pl) * [prog memory friendly.pl](./oeis-research/Robert%20Israel/First%20number%20that%20is%20the%20sum%20of%20k%20successive%20semiprimes%20for%201%20<=%20k%20<=%20n/prog_memory_friendly.pl) diff --git a/oeis-research/Daniel Suteu/First number k such that k + a(i) has n distinct prime factors, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that k + a(i) has n distinct prime factors, for all i < n/prog.sf new file mode 100644 index 0000000..2bc1d96 --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that k + a(i) has n distinct prime factors, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the first number k such that k + a(i) has n distinct prime factors, for all i < n; a(0) = 0. +# https://oeis.org/A?????? + +# Known terms: +# 0, 2, 10, 130, 8930, 1133900, 401424520 + +func a(n) is cached { + + return 0 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.omega_primes_each(lo, hi, {|k| + if (terms.all { is_omega_prime(k + _, n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..10) { + say [n, a(n)] +} diff --git a/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.pl b/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.pl new file mode 100644 index 0000000..89b2a38 --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.pl @@ -0,0 +1,101 @@ +#!/usr/bin/perl + +# a(n) is the first number k such that k + a(i) is the product of n distinct prime factors, for all i < n; a(0) = 0. +# https://oeis.org/A?????? + +# Known terms: +# 0, 2, 33, 1309, 55165, 13386021, 2239003921 + +# Lower-bounds: +# a(7) > 1649267441663, if it exists. + +use 5.036; +use ntheory qw(:all); + +my @terms = (0, 2, 33, 1309, 55165, 13386021, 2239003921); + +sub squarefree_almost_prime_numbers ($A, $B, $k, $callback) { + + $A = vecmax($A, powint(2, $k)); + + my $n = $k; + + sub ($m, $p, $k) { + + if ($k == 1) { + + my $v; + + forprimes { + + $v = $m * $_; + + if ( is_almost_prime($n, $v + $terms[-1]) + and is_almost_prime($n, $v + $terms[-2]) + and is_almost_prime($n, $v + $terms[-3]) + and is_square_free($v + $terms[-1]) + and is_square_free($v + $terms[-2]) + and is_square_free($v + $terms[-3]) + and vecall { is_almost_prime($n, $v + $_) and is_square_free($v + $_) } @terms) { + $callback->($v); + $B = $v if ($v < $B); + lastfor; + } + + } vecmax($p, cdivint($A, $m)), divint($B, $m); + + return; + } + + my $s = rootint(divint($B, $m), $k); + + foreach my $q (@{primes($p, $s)}) { + __SUB__->($m * $q, $q+1, $k - 1); + } + } + ->(1, 2, $k); +} + +my $n = 7; +my $lo = 2; +my $hi = 2 * $lo; + +say "\n:: Searching for a($n)\n"; + +while (1) { + + say "Sieving: [$lo, $hi]"; + + my @terms; + squarefree_almost_prime_numbers( + $lo, $hi, $n, + sub($k) { + say "Found upper-bound: a($n) <= $k"; + push @terms, $k; + } + ); + + @terms = sort { $a <=> $b } @terms; + + if (@terms) { + say "New term: a($n) = $terms[0]\n"; + last; + } + + $lo = $hi + 1; + $hi = 2 * $lo; +} + +__END__ + +Sieving: [805306367, 1610612734] +Sieving: [1610612735, 3221225470] +Found upper-bound: a(6) <= 2239003921 +New term: a(6) = 2239003921 + +perl prog.pl 28.40s user 0.04s system 92% cpu 30.751 total + +Sieving: [824633720831, 1649267441662] +Sieving: [1649267441663, 3298534883326] +^C +perl prog.pl 6250.60s user 14.21s system 84% cpu 2:03:41.07 total diff --git a/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.sf new file mode 100644 index 0000000..1b13105 --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that k + a(i) is the product of n distinct prime factors, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the first number k such that k + a(i) is the product of n distinct prime factors, for all i < n; a(0) = 0. +# https://oeis.org/A?????? + +# Known terms: +# 0, 2, 33, 1309, 55165, 13386021, 2239003921 + +func a(n) is cached { + + return 0 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.squarefree_almost_primes_each(lo, hi, {|k| + if (terms.all { is_squarefree_almost_prime(k + _, n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..10) { + say "a(#{n}) = #{a(n)}" +} diff --git a/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n distinct prime factors, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n distinct prime factors, for all i < n/prog.sf new file mode 100644 index 0000000..e20c66e --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n distinct prime factors, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the irst number k such that the concatenation of a(i) and k has n distinct prime factors, for all i < n; a(0) = 0. +# https://oeis.org/A?????? + +# Known terms: +# 0, 2, 6, 66, 210, 22110, 9958740 + +func a(n) is cached { + + return 0 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.omega_primes_each(lo, hi, {|k| + if (terms.all { is_omega_prime(Num(join('', _, k)), n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..10) { + say "a(#{n}) = #{a(n)}" +} diff --git a/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n prime factors, counted with multiplicity, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n prime factors, counted with multiplicity, for all i < n/prog.sf new file mode 100644 index 0000000..2a26dbc --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that the concatenation of a(i) and k has n prime factors, counted with multiplicity, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the irst number k such that the concatenation of a(i) and k has n prime factors, counted with multiplicity, for all i < n; a(0) = 0. +# https://oeis.org/A?????? + +# Known terms: +# 0, 2, 6, 8, 152, 920, 2256, 57824, 223520, 612500, 14103168, 110125568 + +func a(n) is cached { + + return 0 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.almost_primes_each(lo, hi, {|k| + if (terms.all { is_almost_prime(Num(join('', _, k)), n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..100) { + say "a(#{n}) = #{a(n)}" +} diff --git a/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n distinct prime factors, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n distinct prime factors, for all i < n/prog.sf new file mode 100644 index 0000000..92fb309 --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n distinct prime factors, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the irst number k such that the concatenation of k and a(i) has n distinct prime factors, for all i < n; a(0) = 1. +# https://oeis.org/A?????? + +# Known terms: +# 1, 3, 14, 804, 48330, 16579170 + +func a(n) is cached { + + return 1 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.omega_primes_each(lo, hi, {|k| + if (terms.all { is_omega_prime(Num(join('', k, _)), n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..10) { + say "a(#{n}) = #{a(n)}" +} diff --git a/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n prime factors, counted with multiplicity, for all i < n/prog.sf b/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n prime factors, counted with multiplicity, for all i < n/prog.sf new file mode 100644 index 0000000..45138fe --- /dev/null +++ b/oeis-research/Daniel Suteu/First number k such that the concatenation of k and a(i) has n prime factors, counted with multiplicity, for all i < n/prog.sf @@ -0,0 +1,30 @@ +#!/usr/bin/ruby + +# a(n) is the irst number k such that the concatenation of k and a(i) has n prime factors, counted with multiplicity, for all i < n; a(0) = 1. +# https://oeis.org/A?????? + +# Known terms: +# 1, 3, 9, 555, 18762, 1516626 + +func a(n) is cached { + + return 1 if (n == 0); + var terms = (^n -> map(a).flip) + + var lo = 1 + var hi = 2*lo + + loop { + n.almost_primes_each(lo, hi, {|k| + if (terms.all { is_almost_prime(Num(join('', k, _)), n) }) { + return k + } + }) + lo = hi+1 + hi = 2*lo + } +} + +for n in (1..100) { + say "a(#{n}) = #{a(n)}" +} diff --git a/oeis-research/J.W.L. (Jan) Eerland/Smallest k such that 3^(4*3^n) - k is a safe prime/prog.sf b/oeis-research/J.W.L. (Jan) Eerland/Smallest k such that 3^(4*3^n) - k is a safe prime/prog.sf new file mode 100644 index 0000000..61fd659 --- /dev/null +++ b/oeis-research/J.W.L. (Jan) Eerland/Smallest k such that 3^(4*3^n) - k is a safe prime/prog.sf @@ -0,0 +1,52 @@ +#!/usr/bin/ruby + +# Smallest k such that 3^(4*3^n) - k is a safe prime. +# https://oeis.org/A376946 + +# Known terms: +# 22, 202, 6934, 634, 109678, 445294, 2323138 + +# Lower-bounds: +# a(7) > 23348433 + +func a(n, from=1) { + + var prefix = 3**(4 * 3**n) + var len = prefix.len + + for k in (from .. Inf) { + say "Testing: #{k} (length: #{len})" + + local Num!USE_PFGW = false + + if (primality_pretest(prefix - k) && primality_pretest((prefix - k - 1)>>1)) { + + local Num!USE_PFGW = true + + if (prefix - k -> is_safe_prime) { + return k + } + } + } +} + +var n = 7 +var from = 23348433 + +say "a(#{n}) = #{a(n, from)}" + +#for n in (0..100) { +# say [n, a(n)] +#} + +__END__ +[0, 22] +[2, 6934] +[3, 634] +[4, 109678] +[5, 445294] +[6, 2323138] + +Testing: 14194858 (length: 4174) +^C +/home/swampyx/Other/Programare/sidef/bin/sidef -N prog.sf 20260.40s user 1064.73s system 95% cpu 6:13:50.82 total diff --git a/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/prog.pl b/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/prog.pl new file mode 100644 index 0000000..113d7a0 --- /dev/null +++ b/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/prog.pl @@ -0,0 +1,122 @@ +#!/usr/bin/perl + +# a(n) is the first number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n; a(0) = 0. +# https://oeis.org/A361228 + +# Known terms: +# 0, 2, 4, 66, 1012, 14630, 929390, 63798350 + +# New terms: +# a(8) = 19371451550 + +# Lower-bounds: +# a(9) > 824633720831 + +use 5.036; +use ntheory qw(:all); + +my @terms = (0, 2, 4, 66, 1012, 14630, 929390, 63798350, 19371451550); + +sub almost_prime_numbers ($A, $B, $k, $callback) { + + $A = vecmax($A, powint(2, $k)); + + my $n = $k; + + sub ($m, $p, $k) { + + if ($k == 1) { + + my $v; + + forprimes { + + $v = $m * $_; + + if ( is_almost_prime($n, $v + $terms[-1]) + and is_almost_prime($n, $v + $terms[-2]) + and is_almost_prime($n, $v + $terms[-3]) + and vecall { is_almost_prime($n, $v + $_) } @terms) { + $callback->($v); + $B = $v if ($v < $B); + lastfor; + } + + } vecmax($p, cdivint($A, $m)), divint($B, $m); + + return; + } + + my $s = rootint(divint($B, $m), $k); + + foreach my $q (@{primes($p, $s)}) { + __SUB__->($m * $q, $q, $k - 1); + } + } + ->(1, 2, $k); +} + +my $n = 9; +my $lo = 2; +my $hi = 2 * $lo; + +say "\n:: Searching for a($n)\n"; + +while (1) { + + say "Sieving: [$lo, $hi]"; + + my @terms; + almost_prime_numbers( + $lo, $hi, $n, + sub($k) { + say "Found upper-bound: a($n) <= $k"; + push @terms, $k; + } + ); + + @terms = sort { $a <=> $b } @terms; + + if (@terms) { + say "New term: a($n) = $terms[0]\n"; + last; + } + + $lo = $hi + 1; + $hi = 2 * $lo; +} + +__END__ +:: Searching for a(7) + +Sieving: [929391, 1858782] +Sieving: [1858783, 3717566] +Sieving: [3717567, 7435134] +Sieving: [7435135, 14870270] +Sieving: [14870271, 29740542] +Sieving: [29740543, 59481086] +Sieving: [59481087, 118962174] +Found upper-bound: a(7) <= 63798350 +New term: a(7) = 63798350 + +:: Searching for a(8) + +Sieving: [63798351, 127596702] +Sieving: [127596703, 255193406] +Sieving: [255193407, 510386814] +Sieving: [510386815, 1020773630] +Sieving: [1020773631, 2041547262] +Sieving: [2041547263, 4083094526] +Sieving: [4083094527, 8166189054] +Sieving: [8166189055, 16332378110] +Sieving: [16332378111, 32664756222] +Found upper-bound: a(8) <= 19371451550 +New term: a(8) = 19371451550 + +perl prog.pl 462.44s user 0.42s system 92% cpu 8:18.36 total + +Sieving: [206158430207, 412316860414] +Sieving: [412316860415, 824633720830] +Sieving: [824633720831, 1649267441662] +^C +perl prog.pl 13057.94s user 21.68s system 87% cpu 4:09:52.99 total diff --git a/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/upperbounds.pl b/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/upperbounds.pl new file mode 100644 index 0000000..a2bcfdb --- /dev/null +++ b/oeis-research/Robert Israel/First number k such that k + a(i) has n prime factors, counted with multiplicity, for all i < n/upperbounds.pl @@ -0,0 +1,23 @@ +#!/usr/bin/perl + +use 5.036; +use ntheory qw(:all); + +my @terms = (0, 2, 4, 66, 1012, 14630, 929390, 63798350, 19371451550); + +my $prefix = 40150; + +my $n = 9; + +foralmostprimes { + + my $t = $prefix * $_; + + if ( is_almost_prime($n, $t + $terms[-1]) + and is_almost_prime($n, $t + $terms[-2]) + and is_almost_prime($n, $t + $terms[-3]) + and vecall { is_almost_prime($n, $t + $_) } @terms) { + die "Found: a($n) <= $t"; + } + +} $n - prime_bigomega($prefix), 1e9; diff --git a/oeis-research/Zak Seidov/First number k such that Omega(k) = n and Omega(n - 1) = Omega(n + 1) = n + 1/generate.pl b/oeis-research/Zak Seidov/First number k such that Omega(k) = n and Omega(n - 1) = Omega(n + 1) = n + 1/generate.pl index cade179..e6e4ed1 100644 --- a/oeis-research/Zak Seidov/First number k such that Omega(k) = n and Omega(n - 1) = Omega(n + 1) = n + 1/generate.pl +++ b/oeis-research/Zak Seidov/First number k such that Omega(k) = n and Omega(n - 1) = Omega(n + 1) = n + 1/generate.pl @@ -7,7 +7,7 @@ # 5, 51, 343, 3185, 75951, 1780624, 16825375, 212781249 # New terms: -# a(9) = 4613781249 +# a(9) = 4613781249 # a(10) = 74239460225 # a(11) = 858245781249