A289857 Primes of the form k!2 - 512, where k!2 is the double factorial number (A006882).

433, 9883, 13749310063, 316234142713, 25373791335626257947657608863, 7297912393562140321551086320493608726062890113, 79777941814291672401518892224505807820921910393015244140113

Offset: 1

Author

Robert Price, Jul 13 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..10
• Henri and Renaud Lifchitz, PRP Records.Search for n!2-512.
• Joe McLean, Interesting Sources of Probable Primes.
• OpenPFGW Project, Primality Tester.

Crossrefs

Cf. A006882, A258452.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 2] - 512, {i, 9, 100}], PrimeQ[#]&]

Formula

a(n) = A006882(A258452(n)) - 512. - Elmo R. Oliveira, Apr 14 2025