larger_fermat_from_fermat_simple.sf

#!/usr/bin/ruby

# Generate larger Fermat pseudoprimes to base 2 from smaller pseudoprimes.

ARGF.each {|line|

    var n = line.nums.tail || next
    var L = znorder(2,n)

    for d in ((n.dec / L).divisors) {

        var p = (L*d + 1)

        p.is_prime || next
        p `divides` n && next

        assert(is_psp(n*p))
        say n*p
    }
}