login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180628 Numbers k such that 7*k! - 1 is prime. 8
2, 3, 4, 5, 6, 7, 8, 12, 23, 25, 31, 57, 74, 86, 140, 240, 310, 703, 713, 796, 1028, 1102, 1924 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(24) > 2589. - Jinyuan Wang, Feb 03 2020

LINKS

Table of n, a(n) for n=1..23.

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

MATHEMATICA

fQ[n_] := PrimeQ[7 n! - 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst

PROG

(PARI) is(k) = ispseudoprime(7*k!-1); \\ Jinyuan Wang, Feb 03 2020

CROSSREFS

Cf. A002982, A076133, A076134, A099350, A099351, A180627, A180629, A180630, A180631.

Sequence in context: A033087 A084589 A271831 * A165306 A254116 A254115

Adjacent sequences:  A180625 A180626 A180627 * A180629 A180630 A180631

KEYWORD

nonn,more

AUTHOR

Robert G. Wilson v, Sep 13 2010

EXTENSIONS

a(23) from Jinyuan Wang, Feb 03 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 11 09:54 EDT 2021. Contains 342886 sequences. (Running on oeis4.)