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A289699
Numbers k such that k!6 - 32 is prime, where k!6 is the sextuple factorial number (A085158).
1
11, 13, 15, 19, 33, 35, 39, 59, 63, 75, 105, 143, 187, 213, 271, 307, 431, 549, 1211, 1597, 1879, 2025, 3085, 5995, 5997, 6697, 6795, 10543, 21515, 25811, 34345, 57561, 70797, 71671
OFFSET
1,1
COMMENTS
Corresponding primes are: 23, 59, 373, 1697, 7577923, 21827543, 295540213, ...
a(35) > 10^5.
Terms > 39 correspond to probable primes.
EXAMPLE
15!6 - 32 = 15*9*3 - 32 = 373 is prime, so 15 is in the sequence.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[10, 50000], PrimeQ[MultiFactorial[#, 6] - 32] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Jul 09 2017
EXTENSIONS
a(32)-a(34) from Robert Price, Aug 04 2018
STATUS
approved