A288154 Numbers k such that k!6 + 9 is prime, where k!6 is the sextuple factorial number (A085158 ).

2, 4, 14, 28, 34, 46, 50, 52, 86, 100, 106, 140, 166, 170, 208, 242, 338, 344, 412, 1360, 2024, 2948, 3650, 5608, 5744, 7618, 8410, 8834, 11872, 12514, 13636, 18742, 20846, 29750, 31312

Offset

1,1

Comments

Corresponding primes are: 11, 13, 233, 394249, 13404169, 24663654409, 311607296009, ...

a(36) > 50000.

Terms > 50 correspond to probable primes.

Links

Table of n, a(n) for n=1..35.

Henri & Renaud Lifchitz, PRP Records. Search for n!6+9.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

14!6 + 9 = 14*8*2 + 9 = 233 is prime, so 14 is in the sequence.

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 9] &]

Crossrefs

Cf. A007661, A037082, A084438, A123910, A242994.

Sequence in context: A036051 A115626 A116021 * A283353 A323656 A338740

Adjacent sequences: A288151 A288152 A288153 * A288155 A288156 A288157

Keyword

nonn,more

Author

Robert Price, Jun 05 2017

Status

approved