A283553 Numbers k such that k![4] + 2 is prime, where k![4] = A007662(k) = quadruple factorial.

0, 1, 3, 5, 7, 9, 11, 13, 15, 19, 27, 29, 31, 43, 53, 75, 143, 169, 185, 235, 259, 363, 365, 457, 493, 573, 777, 1273, 1275, 1865, 3621, 4523, 5291, 5845, 7185, 10183, 12845, 15057, 16281, 17945, 18771, 22479, 27235, 28089, 31557, 39163, 45709, 46329, 52211, 77779

Offset

1,3

Comments

a(51) > 10^5.

The first 10 primes associated with this sequence: 3, 3, 5, 7, 23, 47, 233, 587, 3467, 65837.

Links

Table of n, a(n) for n=1..50.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75

Ken Davis, Status of Search for Multifactorial Primes.

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 4] + 2] &]
Select[Range[0, 78000], PrimeQ[Times@@Range[#, 1, -4]+2]&] (* Harvey P. Dale, Aug 16 2023 *)

Crossrefs

Cf. A076185, A085158, A094144, A204657.

Sequence in context: A192861 A333854 A192868 * A081110 A143449 A033034

Adjacent sequences: A283550 A283551 A283552 * A283554 A283555 A283556

Keyword

nonn

Author

Robert Price, Mar 10 2017

Extensions

a(49)-a(50) from Robert Price, Aug 12 2017

Status

approved