A289858 Primes of the form k!2 - 1024, where k!2 is the double factorial number (A006882).

9371, 34458401, 191898783962509601, 319830986772877770814601, 157952079428395476360490147277858351, 2987435000850314871976096554696085799164511452611632783323554397412108351, 283806325080779912837729172696128150920628587998105114415737667754150389601

Offset: 1

Author

Robert Price, Jul 13 2017

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..7
• Henri and Renaud Lifchitz, PRP Records.Search for n!2-1024.
• Joe McLean, Interesting Sources of Probable Primes.
• OpenPFGW Project, Primality Tester.

Crossrefs

Cf. A006882, A258866.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
Select[Table[MultiFactorial[i, 2] - 1024, {i, 10, 100}], PrimeQ[#]&]

Formula

a(n) = A006882(A258866(n)) - 1024. - Elmo R. Oliveira, Apr 15 2025