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

1,1

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

Mathematica

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

Crossrefs

Cf. A243078.

Sequence in context: A342737 A142516 A127874 * A321343 A255889 A154406

Adjacent sequences: A289814 A289815 A289816 * A289818 A289819 A289820

Keyword

nonn

Author

Robert Price, Jul 12 2017

Status

approved