A288715 Primes of the form k!8+1, where k!8 is the octuple factorial number (A114800).

2, 3, 5, 7, 26881, 55441, 96909121, 132843110401, 48704929136641, 152349556104345601, 1397121162877440001, 383414179456168545484801, 81419177249980419349301811609600001, 13189906714496827934586893480755200001

Offset: 1

Author

Robert Price, Jun 13 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..21
• Henri& Renaud Lifchitz, PRP Records.Search for n!8+1.
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester

Crossrefs

Cf. A204661.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 8] + 1, {i, 0, 100}], PrimeQ[#]&]
Select[Table[Times@@Range[n,1,-8]+1,{n,200}],PrimeQ] (* Harvey P. Dale, Dec 26 2022 *)