OFFSET
1,1
COMMENTS
Large terms correspond to probable primes.
a(29) > 50000.
LINKS
Henri & Renaud Lifchitz, PRP Records. Search for n!3+81
Joe McLean, Interesting Sources of Probable Primes
OpenPFGW Project, Primality Tester
Eric Weisstein's World of Mathematics, Multifactorial.
EXAMPLE
7!3 + 81 = 7*4*1 + 81 = 109 is prime, so 7 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] + 81], AppendTo[lst, n]], {n, 100}]; lst
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Sep 25 2014
STATUS
approved