A289850 Primes of the form k!2-4, where k!2 is the double factorial number (A006852).

11, 101, 941, 10391, 135131, 2027021, 654729071, 7905853580621, 221643095476699771871, 79777941814291672401518892224505807820921910393015244140621, 6462013286957625464523030270184970433494674741834234775390621

Offset

1,1

Links

Robert Price, Table of n, a(n) for n = 1..13

Henri & Renaud Lifchitz, PRP Records.Search for n!2-4.

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, 2] - 4, {i, 4, 100}], PrimeQ[#]&]
Select[Range[4, 100]!!-4, PrimeQ] (* Harvey P. Dale, Dec 16 2020 *)

Crossrefs

Cf. A123910.

Sequence in context: A287832 A122105 A332853 * A351811 A171750 A191420

Adjacent sequences: A289847 A289848 A289849 * A289851 A289852 A289853

Keyword

nonn

Author

Robert Price, Jul 13 2017

Status

approved