A101234 Numbers k such that 7^k + 5^k - 1 is prime.

1, 2, 3, 9, 13, 25, 26, 63, 73, 435, 2245, 2907, 3089, 5615, 20113, 20355

Offset

1,2

Comments

Terms beyond 435 are (BSW-)pseudoprimes. - Joerg Arndt, Jan 25 2011

Links

Table of n, a(n) for n=1..16.

Prog

(Magma) [n: n in [0..400]|IsPrime(7^n+5^n-1)]
(PARI) for(n=1, 10000, if(isprime(7^n+5^n-1), print1(n, ", ")))  /* Joerg Arndt, Jan 25 2011 */

Crossrefs

Sequence in context: A032486 A123859 A048744 * A233190 A269154 A358829

Adjacent sequences: A101231 A101232 A101233 * A101235 A101236 A101237

Keyword

nonn,more

Author

Vincenzo Librandi, Jan 22 2011

Extensions

a(11)-a(13) from Joerg Arndt, Jan 25 2011

a(14) from Vincenzo Librandi, Jul 28 2020

a(15)-a(16) from Michael S. Branicky, Apr 29 2023

Status

approved