A284190 Numbers k such that k![14]-2 is prime, where k![14] is the fourteen-fold multifactorial.

4, 5, 7, 9, 13, 15, 27, 29, 31, 39, 41, 45, 59, 61, 75, 83, 87, 107, 123, 153, 159, 229, 255, 333, 343, 381, 399, 469, 599, 671, 707, 735, 737, 745, 797, 981, 1115, 1121, 1233, 1545, 1625, 1943, 2177, 2355, 2593, 2875, 2891, 6779, 6937, 7717, 7767, 9947, 12285, 13411, 15367, 15457, 15699, 17319, 18035, 20617, 33125, 37449, 56353, 61869, 80599

Offset

1,1

Comments

a(66) > 100000.

The first 12 primes associated with this sequence: 2, 3, 5, 7, 11, 13, 349, 433, 1579, 10723, 14389, 71143.

k = 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 32, 51, 72, 95, 120.

Links

Table of n, a(n) for n=1..65.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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, 100000], PrimeQ[MultiFactorial[#, 14] - 2] &]

Prog

(PARI) M(n, k) = if(n<1, 1, n*M(n - k, k));
isok(n) = isprime(M(n, 14) - 2); \\ Indranil Ghosh, Mar 22 2017

Crossrefs

Sequence in context: A052147 A139690 A283559 * A035266 A035264 A234257

Adjacent sequences: A284187 A284188 A284189 * A284191 A284192 A284193

Keyword

nonn

Author

Robert Price, Mar 22 2017

Status

approved