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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 (list; graph; refs; listen; history; text; internal format)
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!6-3.

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: A151976 A074819 A113935 * A291640 A088766 A091091

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

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Last modified May 23 20:23 EDT 2019. Contains 323528 sequences. (Running on oeis4.)