experimental-projects/oeis-research/Thomas Ordowski/24 May/sidef_prog.sf

#!/usr/bin/ruby
func isok(n) {
    var m = znorder(2, n)
    m.is_even || return false
    m < euler_phi(n) || return false
    powmod(2, m/2, n).is_congruent(-1, n)
}

for k in (1..3000) {
    if (isok(k)) {
        print(k, ", ")
    }
}