A143279 Numbers n such that 6*5^n + 1 is prime.

0, 1, 2, 3, 23, 27, 33, 63, 158, 278, 290, 351, 471, 797, 8462, 28793, 266030

Offset: 1

Author

Rick L. Shepherd, Aug 04 2008

Keywords

• hard
• nonn

Comments

Primes found and proved by PrimeForm.

All terms correspond to verified primes, that is, not merely probable primes. - Robert Price, Jan 16 2015

a(18) > 3*10^5. - Robert Price, Jan 16 2015

Programs

Mathematica

Select[Range[0, 10000], PrimeQ[6*5^# + 1] &] (* Robert Price, Jan 16 2015 *)

PARI

is(n)=ispseudoprime(6*5^n+1) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

a(17) from Robert Price, Jan 16 2015