A287207 Numbers k such that k![6] + 2 is prime, where k![6] = A085158(k) = sextuple factorial.

0, 1, 3, 5, 9, 17, 27, 45, 51, 53, 93, 197, 213, 221, 245, 279, 845, 927, 2055, 2895, 3615, 5613, 12753, 15737, 17813, 18545, 22629, 47859, 48797

Offset

1,3

Comments

a(30) > 50000.

The first 7 primes associated with this sequence: 3, 3, 5, 7, 29, 937, 229637.

Links

Table of n, a(n) for n=1..29.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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[#, 6] + 2] &]
Select[Range[0, 10000], PrimeQ[Times@@Range[#, 1, -6]+2]&] (* The program generates the first 22 terms of the sequence. *) (* Harvey P. Dale, Dec 27 2022 *)

Crossrefs

Cf. A076185, A085158, A094144, A204657.

Sequence in context: A032679 A154607 A361875 * A298338 A018162 A077879

Adjacent sequences: A287204 A287205 A287206 * A287208 A287209 A287210

Keyword

nonn

Author

Robert Price, May 21 2017

Status

approved