A180627 Numbers k such that 6*k! - 1 is prime.

0, 1, 2, 5, 8, 42, 318, 326, 1054, 2987, 11243

Offset

1,3

Comments

Tested to 4400. - Robert G. Wilson v, Sep 28 2010

a(11) > 6300. - Jinyuan Wang, Feb 04 2020

Links

Table of n, a(n) for n=1..11.

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

Mathematica

fQ[n_] := PrimeQ[6 n! - 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst

Prog

(PARI) is(k) = ispseudoprime(6*k!-1); \\ Jinyuan Wang, Feb 04 2020

Crossrefs

Cf. A002982, A076133, A076134, A099350, A099351, A180628, A180630, A180630, A180631.

Sequence in context: A214842 A299517 A268660 * A264860 A061354 A162709

Adjacent sequences: A180624 A180625 A180626 * A180628 A180629 A180630

Keyword

nonn,more

Author

Robert G. Wilson v, Sep 13 2010

Extensions

a(10) from Robert G. Wilson v, Sep 28 2010

a(11) from Michael S. Branicky, Jul 04 2024

Status

approved