A287956 Numbers k such that k!6 + 6 is prime, where k!6 is the sextuple factorial number (A085158 ).

1, 5, 7, 11, 13, 17, 37, 43, 55, 107, 139, 149, 157, 211, 223, 343, 373, 409, 523, 12049, 16457, 17143, 17543, 18391, 25829, 25945, 31307, 34601, 41687

Offset

1,2

Comments

Corresponding primes are: 7, 11, 13, 61, 97, 941, 49579081, 2131900231, 5745471106381, ...

a(43) > 50000.

Terms > 35 correspond to probable primes.

Links

Table of n, a(n) for n=1..29.

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

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

11!6 + 6 = 11*5 + 6 = 61 is prime, so 11 is in the sequence.

Mathematica

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

Crossrefs

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

Sequence in context: A230217 A317250 A007529 * A266266 A246463 A314297

Adjacent sequences: A287953 A287954 A287955 * A287957 A287958 A287959

Keyword

nonn,more

Author

Robert Price, Jun 03 2017

Status

approved