A290241 Primes of the form 3^k - 8.

19, 73, 2179, 6553, 4782961, 3486784393, 31381059601, 381520424476945831628649898801, 2088595827392656793085408064780643444068898148936888424953199350259

Offset: 1

Author

Robert Price, Jul 24 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..11
• F. Firoozbakht and M. F. Hasler, Variations on Euclid's formula for Perfect Numbers, JIS 13 (2010) #10.3.1.
• Henri and Renaud Lifchitz, PRP Records
• OpenPFGW Project, Primality Tester

Crossrefs

Cf. A000040, A217135 (corresponding k's).

Programs

Mathematica

Select[Table[3^k - 8, {k, 2, 100}], PrimeQ[#] &]

PARI

lista(nn) = for(n=3, nn, if(isprime(p=3^n-8), print1(p", "))); \\ Altug Alkan, Jul 25 2017

Formula

a(n) = 3^A217135(n) - 8. - Elmo R. Oliveira, Nov 09 2023