A109503 Numbers k such that 66 * 10^k + 1 is prime.

0, 1, 4, 5, 11, 30, 60, 64, 869, 1685, 12109, 39684, 65460, 80064

Offset

1,3

Comments

All terms proved prime. Proof for the largest: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing 66*10^12109+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 7 Calling Brillhart-Lehmer-Selfridge with factored part 69.89% 66*10^12109+1 is prime! (27.9892s+0.0059s). No more terms up to 38800, although another is 65460 found by Peter Benson (listed at Caldwell's Top-5000 Primes site).

Links

Table of n, a(n) for n=1..14.

Makoto Kamada, Search for 660w1.

Prog

(PARI) is(n)=ispseudoprime(66*10^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A216963 A259821 A352681 * A304224 A304135 A251240

Adjacent sequences: A109500 A109501 A109502 * A109504 A109505 A109506

Keyword

nonn

Author

Jason Earls, Aug 29 2005

Extensions

a(12)-a(14) from Kamada data by Tyler Busby, Apr 29 2024

Status

approved