A288881 Primes of the form k!3 + 3^5, where k!3 is the triple factorial number (A007661).

271, 523, 1123, 24344563, 96342643, 608608243, 5577337931669504243, 52580450364682240243, 262134882788466688243, 13106744139423334400243, 694657439389436723200243, 7368624314106569113600243, 12931890526958090978845347074978621685760000243

Offset: 1

Author

Robert Price, Jun 18 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..15
• Henri and Renaud Lifchitz, PRP Records.Search for n!3+3^5.
• Joe McLean, Interesting Sources of Probable Primes.
• OpenPFGW Project, Primality Tester.

Crossrefs

Cf. A007661, A247868.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 3] + 3^5, {i, 0, 100}], PrimeQ[#]&]

Formula

a(n) = 243 + A007661(A247868(n)). - Elmo R. Oliveira, Apr 14 2025