A180629 Numbers k such that 8*k! - 1 is prime.

0, 1, 3, 4, 8, 33, 121, 177, 190, 276, 473, 484, 924, 937, 1722, 2626, 4077, 4464, 6166

Offset: 1

Author

Robert G. Wilson v, Sep 13 2010

Keywords

• nonn
• more

Comments

Tested to 4700. - Robert G. Wilson v, Sep 27 2010

Tested to 5127. - Jinyuan Wang, Feb 03 2020

Tested to 12000. - Michael S. Branicky, Jul 11 2024

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, A180630, A180631.

Programs

Mathematica

fQ[n_] := PrimeQ[8 n! - 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst

PARI

is(k) = ispseudoprime(8*k!-1); \\ Jinyuan Wang, Feb 03 2020

Extensions

a(15)-a(18) from Robert G. Wilson v, Sep 27 2010

a(19) from Michael S. Branicky, May 27 2023