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- #!/usr/bin/ruby
- # a(n) is the least k such that prime(k) * 2^(10^n) - 1 is prime.
- # https://oeis.org/A126716
- # Known terms:
- # 2, 3, 51, 657, 6255
- # a(5) >= primepi(2129)
- var n = 5
- var t = 2**(10**n)
- for p in (primes(2129, 1e6)) {
- say "Testing: #{p}"
- if (t*p - 1 -> is_prob_prime) {
- die "Found: #{p.primepi}"
- }
- }
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