A180630 Numbers k such that 9*k! - 1 is prime.

2, 3, 12, 15, 16, 25, 30, 38, 59, 82, 114, 168, 172, 175, 213, 229, 251, 302, 311, 554, 2538, 3050, 3363, 12316

Offset: 1

Author

Robert G. Wilson v, Sep 13 2010

Keywords

• nonn
• more

Comments

a(22) > 2575. - Jinyuan Wang, Feb 03 2020

Links

• Index entries for sequences related to numbers of primes of the form k*n!+-1

Crossrefs

Cf. A002982, A076133, A076134, A099350, A099351, A180627, A180628, A180629, A180631.

Programs

Mathematica

fQ[n_] := PrimeQ[9 n! - 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst

PARI

is(k) = ispseudoprime(9*k!-1); \\ Jinyuan Wang, Feb 03 2020

Extensions

a(21) from Jinyuan Wang, Feb 03 2020

a(22)-a(23) from Michael S. Branicky, Apr 25 2023

a(24) from Michael S. Branicky, Nov 02 2024