OFFSET
1,1
COMMENTS
Corresponding primes are: 5, 7, 19, 43, 227, 643, 4483, 14083, 116483, 13404163, ...
a(25) > 50000.
Terms > 34 correspond to probable primes.
LINKS
Henri & Renaud Lifchitz, PRP Records. Search for n!6+3.
Joe McLean, Interesting Sources of Probable Primes
OpenPFGW Project, Primality Tester
EXAMPLE
10!6 + 3 = 10*4 + 3 = 43 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] + 3] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Jun 01 2017
STATUS
approved