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

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

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..10.

Formula

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

Example

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

Prog

(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

Crossrefs

Cf. A155623, A177027.

Sequence in context: A272432 A272431 A261961 * A189974 A316184 A359367

Adjacent sequences: A177027 A177028 A177029 * A177031 A177032 A177033

Keyword

nonn,more

Author

Vincenzo Librandi, Dec 09 2010

Extensions

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

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

Status

approved