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A289688

Numbers k such that k!6 - 12 is prime, where k!6 is the sextuple factorial number (A085158).

11, 13, 23, 29, 35, 37, 49, 95, 97, 101, 113, 133, 137, 361, 401, 701, 1027, 1331, 2087, 2743, 7781, 9391, 12787, 12797, 16123, 17317, 21701, 49657, 64661, 72149, 86413

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OFFSET

1,1

COMMENTS

Corresponding primes are: 43, 79, 21493, 623633, 21827563, 49579063, 104463111013, ...

a(32) > 10^5.

Terms > 49 correspond to probable primes.

LINKS

Table of n, a(n) for n=1..31.

Henri & Renaud Lifchitz, PRP Records. Search for n!6-12.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

EXAMPLE

13!6 - 12 = 13*7*1 - 12 = 79 is prime, so 13 is in the sequence.

MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];

Select[Range[8, 50000], PrimeQ[MultiFactorial[#, 6] - 12] &]

CROSSREFS

Cf. A007661, A037082, A084438, A123910, A242994.

Sequence in context: A023232 A075519 A019406 * A080790 A066123 A370011

Adjacent sequences: A289685 A289686 A289687 * A289689 A289690 A289691

KEYWORD

nonn,more

AUTHOR

Robert Price, Jul 09 2017

EXTENSIONS

a(29)-a(31) from Robert Price, Aug 03 2018

STATUS

approved

URL: https://oeis.org/A289688

⇱ A289688 - OEIS