A289808 Primes of the form 3^k - 28.

53, 701, 59021, 14348879, 31381059581, 282429536453, 7625597484959, 50031545098999679, 1144561273430837494885949696399, 26183890704263137277674192438430182020124319, 2120895147045314119491609587512844743630072079

Offset: 1

Author

Robert Price, Sep 02 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..18
• 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, A219047 (corresponding k's).

Programs

Mathematica

Select[Table[3^k - 28, {k, 4, 100}], PrimeQ[#] &]

Formula

a(n) = 3^A219047(n) - 28. - Elmo R. Oliveira, Nov 12 2023