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A288152
Numbers k such that k!6 + 8 is prime, where k!6 is the sextuple factorial number (A085158 ).
1
3, 5, 21, 29, 41, 65, 243, 305, 389, 509, 819, 1653, 7493, 8613, 8619, 10257, 11829, 12977, 15651, 24341, 29367, 31629, 40173
OFFSET
1,1
COMMENTS
Corresponding primes are: 11, 13, 8513, 623653, 894930583, 8549258359016383, ...
a(24) > 50000.
Terms > 41 correspond to probable primes.
EXAMPLE
21!6 + 8 = 21*15*9*3 + 8 = 8513 is prime, so 21 is in the sequence.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 8] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Jun 05 2017
STATUS
approved