prog.sf

#!/usr/bin/ruby

# 3-powerful numbers that can be written as the sum of two coprime 3-powerful numbers.
# https://oeis.org/A297867

# Known terms:
#   776151559, 3518958160000, 11205183603973252067

var upto = 3518958160000

say "Count: #{upto.powerful_count(3)}"

var table = Hash()
var lookup = Set()

for k in (upto.powerful(3)) {
    table{k.rad} := [] << k
    lookup << k
}

var keys = table.keys.map{.to_i}

for i in (^keys.len) {
    var x = keys[i]

    for j in (i+1 .. keys.end) {

        var y = keys[j]

        x.is_coprime(y) || next

        for a in (table{x}), b in (table{y}) {
            if (lookup.has(a+b)) {
                say "#{a+b} = #{a} + #{b}"
            }
        }
    }
}

__END__
776151559 = 756249048 + 19902511
3518958160000 = 1392672604221 + 2126285555779
11205183603973252067 = 5317378991792784000 + 5887804612180468067