A289560 Primes of the form k!4+256, where k!4 is the quadruple factorial number (A007662).

257, 277, 487, 1267389841, 50491808745015763381, 1008407509171875041482378381, 429215532868726286171043772444743140881, 4551830726072842264843919206776501006328381

Offset: 1

Author

Robert Price, Sep 02 2017

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..17
• Henri& Renaud Lifchitz, PRP Records.Search for n!4+256.
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester

Crossrefs

Cf. A291349.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 4] + 256, {i, 0, 100}], PrimeQ[#]&]
Select[Table[256+Times@@Range[n,1,-4],{n,200}],PrimeQ] (* Harvey P. Dale, Nov 04 2024 *)