A199165 Numbers n such that (6^n-11)/5 is prime.

2, 3, 4, 5, 14, 19, 21, 50, 53, 136, 146, 1255, 1448, 1839, 2053, 2496, 4060, 5041, 8410, 14090, 14940, 19759, 29871, 44836, 78175, 114398, 120946, 137845, 461108, 727496, 840316

Offset

1,1

Links

Table of n, a(n) for n=1..31.

Henri & Renaud Lifchitz, PRP Records.

Example

a(4) = 5  because  (6^5-11)/5 = 1553  is prime.

Mathematica

lst={}; Do[If[PrimeQ[(6^n-11)/5], Print[n]; AppendTo[lst, n]], {n, 10^6}]; lst

Prog

(PARI) is(n)=ispseudoprime((6^n-11)/5) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A004062, A165210, A198725.

Sequence in context: A245447 A361947 A037340 * A202423 A171593 A227535

Adjacent sequences: A199162 A199163 A199164 * A199166 A199167 A199168

Keyword

nonn,more

Author

Gilbert Mozzo, Nov 03 2011

Extensions

a(23)-a(28) are probable primes discovered by Paul Bourdelais, Nov 15 2011

a(23)-a(28) independently confirmed as probable primes using Mathematica PrimeQ function by Gilbert Mozzo, Nov 21 2011

a(29) corresponds to a probable prime discovered by Paul Bourdelais, Apr 25 2019

a(30) corresponds to a probable prime discovered by Paul Bourdelais, Aug 12 2019

a(31) corresponds to a probable prime discovered by Paul Bourdelais, Jun 18 2020

Status

approved