A289817 Primes of the form k!3-9, where k!3 is the triple factorial number (A007661).

19, 71, 271, 3631, 58231, 209431, 4188791, 96342391, 17041023991, 72642169591, 2324549427191, 1143053268797439991, 52580450364682239991, 262134882788466687991, 694657439389436723199991, 38900816605808456499199991, 2295148179742698933452799991

Offset: 1

Author

Robert Price, Jul 12 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..24
• Henri & Renaud Lifchitz, PRP Records.Search for n!3-9.
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester

Crossrefs

Cf. A243078.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 3] - 9, {i, 5, 100}], PrimeQ[#]&]