experimental-projects/oeis-research/Labos Elemer/Numbers k such that Cyclotomic(k,k) is prime/prog2.sf

#!/usr/bin/ruby

# Numbers k such that Cyclotomic(2k,k) is prime.
# https://oeis.org/A088817

# Known terms:
#   1, 2, 3, 4, 5, 9, 17, 36, 157, 245, 352, 3977

# No other terms < 4700.

var from = 5286

for k in (from .. 1e6) {
    say "Testing: #{k}"
    if (cyclotomic(2*k, k).is_prob_prime) {
        die "Found: #{k}"
    }
}