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A247467
Numbers n such that n!3 + 3^6 is prime.
0
4, 5, 7, 8, 10, 11, 14, 17, 35, 41, 50, 59, 89, 136, 164, 205, 224, 283, 763, 1034, 1253, 1630, 1820, 3199, 3800, 5080, 6124, 17306, 17398, 20768, 34033, 43607
OFFSET
1,1
COMMENTS
Large terms correspond to probable primes.
a(33) > 50000.
LINKS
Henri & Renaud Lifchitz, PRP Records. Search for n!3+729
OpenPFGW Project, Primality Tester
Eric Weisstein's World of Mathematics, Multifactorial
EXAMPLE
11!3+729 = 11*8*5*2+729 = 1609 is prime, so 11 is in the sequence.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, If[n < k + 1, n, n*MultiFactorial[n - k, k]]];
lst={}; Do[If[PrimeQ[MultiFactorial[n, 3] + 729], AppendTo[lst, n]], {n, 100}]; lst
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Sep 17 2014
STATUS
approved