A288447 Numbers k such that k!6 + 27 is prime, where k!6 is the sextuple factorial number (A085158 ).

2, 4, 8, 10, 14, 20, 22, 26, 32, 40, 110, 116, 142, 148, 200, 370, 854, 1166, 1594, 2164, 4424, 5942, 9086, 13300, 15224, 20482, 22940, 27478, 47486

Offset

1,1

Comments

Corresponding primes are: 29, 31, 43, 67, 251, 4507, 14107, 116507, 3727387, 536166427, ...

a(30) > 50000.

Terms > 40 correspond to probable primes.

Links

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

Henri & Renaud Lifchitz, PRP Records. Search for n!6+27.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

10!6 + 27 = 10*4 + 27 = 67 is prime, so 10 is in the sequence.

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 27] &]
Select[Range[48000], PrimeQ[Times@@Range[#, 1, -6]+27]&] (* Harvey P. Dale, Aug 10 2021 *)

Crossrefs

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

Sequence in context: A292550 A024895 A250310 * A087915 A088967 A200566

Adjacent sequences: A288444 A288445 A288446 * A288448 A288449 A288450

Keyword

nonn,more

Author

Robert Price, Jun 09 2017

Status

approved