A180626 Numbers k such that 9*k! + 1 is prime.

2, 6, 7, 10, 13, 15, 24, 29, 33, 44, 98, 300, 548, 942, 1099, 1176, 1632, 1794, 3676, 3768, 4804, 6499, 8049, 8164, 8917, 10270, 11610, 11959

Offset: 1

Author

Robert G. Wilson v, Sep 13 2010

Keywords

• nonn
• more

Comments

Tested to 4500. - Robert G. Wilson v, Sep 28 2010

a(22) > 5235. - Jinyuan Wang, Feb 05 2020

Links

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

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A126896.

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 05 2020

Extensions

a(17)-a(20) from Robert G. Wilson v, Sep 28 2010

a(21) from Jinyuan Wang, Feb 05 2020

a(22) from Michael S. Branicky, May 27 2023

a(23)-a(28) from Michael S. Branicky, Jul 12 2024