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

1,1

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 n!3-81.

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] - 81, {i, 9, 100}], PrimeQ[#]&]
Select[Table[Times@@Range[n, 1, -3], {n, 8, 150}]-81, PrimeQ] (* Harvey P. Dale, Nov 14 2022 *)

Crossrefs

Cf. A247464.

Sequence in context: A086977 A324628 A216346 * A195523 A163712 A069244

Adjacent sequences: A289816 A289817 A289818 * A289820 A289821 A289822

Keyword

nonn

Author

Robert Price, Jul 12 2017

Status

approved