A288405 Primes of the form k!2+4, where k!2 is the double factorial number (A006852).

5, 7, 19, 109, 10399, 34459429, 6190283353629379, 319830986772877770815629, 563862029680583509947946879, 174865344543353986303948473285124243127671456831640629, 2987435000850314871976096554696085799164511452611632783323554397412109379

Offset: 1

Author

Robert Price, Jun 08 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..11
• Henri& Renaud Lifchitz, PRP Records.Search for n!2+4.
• Joe McLean, Interesting Sources of Probable Primes
• OpenPFGW Project, Primality Tester

Crossrefs

Cf. A076186.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 2] + 4, {i, 0, 100}], PrimeQ[#]&]