

A279646


Numbers k such that k!6  3 is prime, where k!6 is the sextuple factorial number (A085158).


1



5, 6, 8, 10, 68, 82, 92, 98, 118, 286, 796, 878, 1360, 1502, 1516, 1568, 1646, 3628, 3716, 4048, 7982, 12776, 18070, 20594, 29902, 39632, 52988, 53864, 55610, 67448, 85402, 89762
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OFFSET

1,1


COMMENTS

Corresponding primes are: 2, 3, 13, 37, 73569236156415997, ...
a(33) > 10^5.
Terms > 10 correspond to probable primes.


LINKS

Table of n, a(n) for n=1..32.
Henri & Renaud Lifchitz, PRP Records. Search for n!63.
Joe McLean, Interesting Sources of Probable Primes
OpenPFGW Project, Primality Tester


EXAMPLE

10!6  3 = 10*4  3 = 37 is prime, so 10 is in the sequence.


MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n  k, k]];
Select[Range[4, 50000], PrimeQ[MultiFactorial[#, 6]  3] &]


CROSSREFS

Cf. A007661, A037082, A084438, A123910, A242994.
Sequence in context: A074819 A330916 A113935 * A291640 A088766 A332549
Adjacent sequences: A279643 A279644 A279645 * A279647 A279648 A279649


KEYWORD

nonn,more


AUTHOR

Robert Price, Jul 07 2017


EXTENSIONS

a(27)a(32) from Robert Price, Aug 03 2018


STATUS

approved



