prog.sf

#!/usr/bin/ruby

# Smallest number m such that m and reverse(m) each have n distinct prime factors.
# https://oeis.org/A239696

# Known terms:
#   2, 6, 66, 858, 6006, 204204, 10444434, 208888680, 6172882716

# New terms (a(10)-a(12)):
#   231645546132, 49795711759794, 2400532020354468

#`(

# PARI/GP program:

generate(A, B, n) = A=max(A, vecprod(primes(n))); (f(m, p, j) = my(list=List()); forprime(q=p, sqrtnint(B\m, j), my(v=m*q); while(v <= B, if(j==1, if(v>=A && omega(fromdigits(Vecrev(digits(v)))) == n, listput(list, v)), if(v*(q+1) <= B, list=concat(list, f(v, q+1, j-1)))); v *= q)); list); vecsort(Vec(f(1, 2, n)));
a(n) = my(x=vecprod(primes(n)), y=2*x); while(1, my(v=generate(x, y, n)); if(#v >= 1, return(v[1])); x=y+1; y=2*x); \\ ~~~~

)

func a(n, from = n.pn_primorial, upto = 2*from) {
    loop {
        n.omega_primes(from, upto).each {|v|
            v.reverse.is_omega_prime(n) || next
            return v
        }
        from = upto+1
        upto *= 2
    }
}

for n in (1..100) { print(a(n), ", ") }