A289819 Primes of the form k!3-81, where k!3 is the triple factorial number (A007661).

199, 3559, 12239, 209359, 4188719, 2504902319, 72642169519, 528271743919, 2324549427119, 13106744139423334399919, 2295148179742698933452799919, 254451773522587035734629406212095999919, 281238294844900882734503454910185471999919

Offset: 1

Author

Robert Price, Jul 12 2017

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..32 (first 19 terms from Robert Price)
• Henri & Renaud Lifchitz, PRP Records. Search for k!3-81.
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester.

Crossrefs

Cf. A247464.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 3] - 81, {i, 9, 100}], PrimeQ[#]&]
Select[Table[Times@@Range[n,1,-3],{n,8,150}]-81,PrimeQ] (* Harvey P. Dale, Nov 14 2022 *)