A177030 Numbers k such that 11^k + 3^k - 1 is prime.

1, 7, 9, 33, 127, 153, 2327, 3607, 14803, 16431

Offset: 1

Author

Vincenzo Librandi, Dec 09 2010

Keywords

• nonn
• more

Comments

a(9) > 13518. - Daniel Starodubtsev, Apr 06 2020

Examples

			7 is in the sequence, because 11^7 + 3^7 - 1 = 19489357 is prime.
		

Crossrefs

Cf. A155623, A177027.

Programs

Magma

[n: n in [0..1500]|IsPrime(11^n+3^n-1^n)]

PARI

is(n)=ispseudoprime(11^n+3^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Formula

A177027(n) = 11^a(n)+3^a(n)-1.

Extensions

a(7)-a(8) from Daniel Starodubtsev, Apr 06 2020

a(9)-a(10) from Michael S. Branicky, Jul 15 2023