A283554 Numbers k such that k![4] - 2 is prime, where k![4] = A007662(k) = quadruple factorial.

4, 5, 7, 9, 11, 15, 21, 25, 29, 49, 79, 87, 95, 125, 133, 153, 157, 185, 201, 217, 223, 289, 323, 469, 533, 567, 821, 1001, 1999, 2523, 2533, 2827, 2843, 4821, 8153, 8947, 12739, 19353, 22929, 30629, 31809, 37785, 74913, 97411

Offset

1,1

Comments

a(45) > 10^5.

The first 9 primes associated with this sequence: 2, 3, 19, 43, 229, 3463, 208843, 5221123, 151412623.

Links

Table of n, a(n) for n=1..44.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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[#, 4] - 2] &]

Crossrefs

Cf. A076185, A085158, A094144, A204657.

Sequence in context: A050560 A204664 A349482 * A035243 A035255 A341787

Adjacent sequences: A283551 A283552 A283553 * A283555 A283556 A283557

Keyword

nonn

Author

Robert Price, Mar 10 2017

Extensions

a(43)-a(44) from Robert Price, Jul 24 2017

Status

approved