A289701 Numbers k such that k!6 - 48 is prime, where k!6 is the sextuple factorial number (A085158).

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

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 A356383 A335976

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