A288883 Primes of the form k!3 + 3^7, where k!3 is the triple factorial number (A007661).

2267, 2467, 3067, 5827, 60427, 1108747, 4190987, 24346507, 664565853954187, 3091650738178187, 262134882788466690187, 571241722682644258978777268224002187, 1189733928480144370053771930898033195089920002187, 17994728558292550488813850298696914425610240002187

Offset: 1

Author

Robert Price, Jun 18 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..18
• Henri and Renaud Lifchitz, PRP Records.Search for n!3+3^7.
• Joe McLean, Interesting Sources of Probable Primes.
• OpenPFGW Project, Primality Tester.

Crossrefs

Cf. A007661, A265200.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 3] + 3^7, {i, 0, 100}], PrimeQ[#]&]

Formula

a(n) = 2187 + A007661(A265200(n)). - Elmo R. Oliveira, Apr 14 2025