A289700 Numbers k such that k!6 - 36 is prime, where k!6 is the sextuple factorial number (A085158).

11, 19, 25, 55, 61, 113, 131, 133, 439, 529, 1079, 1621, 2609, 2825, 3997, 4235, 5081, 7319, 8365, 9023, 10273, 18095, 18199, 22625, 24535, 27229, 28883, 99877

Offset

1,1

Comments

Corresponding primes are: 19, 1693, 43189, 5745471106339, 350473737488839, ...

a(29) > 10^5.

Terms > 25 correspond to probable primes.

Links

Table of n, a(n) for n=1..28.

Henri & Renaud Lifchitz, PRP Records. Search for n!6-36.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

19!6 - 36 = 19*13*7*1 - 36 = 1693 is prime, so 19 is in the sequence.

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[10, 50000], PrimeQ[MultiFactorial[#, 6] - 36] &]

Crossrefs

Cf. A007661, A037082, A084438, A085158, A123910, A242994.

Sequence in context: A089172 A152567 A029481 * A231012 A231007 A129916

Adjacent sequences: A289697 A289698 A289699 * A289701 A289702 A289703

Keyword

nonn,more

Author

Robert Price, Jul 09 2017

Extensions

a(28) from Robert Price, Nov 28 2018

Status

approved