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A289701 Numbers k such that k!6 - 48 is prime, where k!6 is the sextuple factorial number (A085158). 1
11, 13, 17, 25, 35, 41, 73, 77, 89, 113, 115, 121, 125, 137, 155, 169, 287, 521, 709, 721, 1999, 2333, 3029, 4067, 6343, 6773, 11065, 14095, 29969, 36181, 50155, 60973, 84731, 88769 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding primes are: 7, 43, 887, 43177, 21827527, 894930527, 1714167050058087577, ...

a(35) > 10^5.

Terms > 41 correspond to probable primes.

LINKS

Table of n, a(n) for n=1..34.

Henri & Renaud Lifchitz, PRP Records. Search for n!6-48.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

EXAMPLE

13!6 - 48 = 13*7*1 - 48 = 43 is prime, so 13 is in the sequence.

MATHEMATICA

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

Select[Range[11, 50000], PrimeQ[MultiFactorial[#, 6] - 48] &]

CROSSREFS

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

Sequence in context: A106076 A006489 A032621 * A250402 A052031 A166009

Adjacent sequences:  A289698 A289699 A289700 * A289702 A289703 A289704

KEYWORD

nonn,more

AUTHOR

Robert Price, Jul 09 2017

EXTENSIONS

a(31)-a(34) from Robert Price, Aug 04 2018

STATUS

approved

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Last modified February 18 02:57 EST 2020. Contains 332006 sequences. (Running on oeis4.)