A283485 Numbers k such that k![6]-2 is prime, where k![6] = A085158 (k) = sextuple factorial.

4, 5, 7, 11, 13, 23, 25, 31, 33, 37, 59, 63, 91, 157, 265, 267, 327, 539, 555, 621, 715, 921, 979, 1633, 1821, 2259, 2697, 2809, 2863, 2935, 4213, 4351, 5937, 6885, 8743, 10761, 15159, 17685, 52075, 55147, 68677, 99655

Offset

1,1

Comments

a(43) > 10^5.

The first 10 primes associated with this sequence: 2, 3, 5, 53, 89, 21503, 43223, 1339973, 7577953, 49579073.

Links

Table of n, a(n) for n=1..42.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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[2, 50000], PrimeQ[MultiFactorial[#, 6] - 2] &]
Select[Range[100000], PrimeQ[Times@@Range[#, 1, -6]-2]&] (* Harvey P. Dale, Feb 23 2023 *)

Crossrefs

Cf. A076185, A085158, A094144, A204657.

Sequence in context: A084087 A175903 A080327 * A184778 A240118 A343211

Adjacent sequences: A283482 A283483 A283484 * A283486 A283487 A283488

Keyword

nonn

Author

Robert Price, Mar 08 2017

Extensions

a(39)-a(42) from Robert Price, Jul 09 2017

Status

approved