A186106 Numbers k such that 3*6^k - 1 is prime.

0, 1, 2, 3, 5, 6, 9, 12, 13, 24, 41, 71, 140, 189, 190, 630, 713, 1066, 1173, 1202, 1271, 1520, 1606, 2091, 2162, 2547, 6253, 7284, 8676, 10735, 12954, 22042, 32457, 36693, 50715, 72313

Offset: 1

Author

Gilbert Mozzo, Feb 12 2011

Keywords

• nonn
• more

Comments

a(37) > 1*10^5. - Tyler NeSmith, Oct 03 2022

Crossrefs

See A186104 for the actual primes; cf. A185167.

Programs

Mathematica

lst={}; Do[If[PrimeQ[(3*6^n-1)], Print[n]; AppendTo[lst, n]], {n, 10^5}];

PARI

is(n)=ispseudoprime(3*6^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(17)-a(25) computed by Bruno Berselli, Feb 12 2011 and Feb 21 2011

a(26)-a(33) computed by Gilbert Mozzo, Nov 16 2011 with Mathematica

a(34)-a(35) computed by Gilbert Mozzo, Nov 08 2018 with PARI

a(36) from Tyler NeSmith, Oct 03 2022