A289699 Numbers k such that k!6 - 32 is prime, where k!6 is the sextuple factorial number (A085158).

11, 13, 15, 19, 33, 35, 39, 59, 63, 75, 105, 143, 187, 213, 271, 307, 431, 549, 1211, 1597, 1879, 2025, 3085, 5995, 5997, 6697, 6795, 10543, 21515, 25811, 34345, 57561, 70797, 71671

Offset

1,1

Comments

Corresponding primes are: 23, 59, 373, 1697, 7577923, 21827543, 295540213, ...

a(35) > 10^5.

Terms > 39 correspond to probable primes.

Links

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

Henri & Renaud Lifchitz, PRP Records. Search for n!6-32.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Example

15!6 - 32 = 15*9*3 - 32 = 373 is prime, so 15 is in the sequence.

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[10, 50000], PrimeQ[MultiFactorial[#, 6] - 32] &]

Crossrefs

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

Sequence in context: A179084 A124569 A260826 * A049722 A099481 A254412

Adjacent sequences: A289696 A289697 A289698 * A289700 A289701 A289702

Keyword

nonn,more

Author

Robert Price, Jul 09 2017

Extensions

a(32)-a(34) from Robert Price, Aug 04 2018

Status

approved