login
A288447
Numbers k such that k!6 + 27 is prime, where k!6 is the sextuple factorial number (A085158 ).
1
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.
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
KEYWORD
nonn,more
AUTHOR
Robert Price, Jun 09 2017
STATUS
approved