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

Author

Robert Price, May 21 2017

Keywords

• nonn

Comments

a(30) > 50000.

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

Links

• C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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

Crossrefs

Cf. A076185, A085158, A094144, A204657.

Programs

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 *)