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A099351 Numbers k such that 5*k! - 1 is prime. 10
3, 5, 8, 13, 20, 25, 51, 97, 101, 241, 266, 521, 1279, 1750 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(15) > 1879. - Jinyuan Wang, Feb 04 2020

LINKS

Table of n, a(n) for n=1..14.

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

EXAMPLE

k = 5 is here because 5*5! - 1 = 599 is prime.

MAPLE

for n from 0 to 1000 do if isprime(5*n! - 1) then print(n) end if end do;

MATHEMATICA

Select[Range[550], PrimeQ[5#!-1]&] (* Harvey P. Dale, Nov 27 2013 *)

PROG

(PARI) is(n)=ispseudoprime(5*n!-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A002982, A076133, A076134, A099350, A180627, A180628, A180629, A180630, A180631.

Sequence in context: A035421 A035424 A245934 * A265065 A265066 A265067

Adjacent sequences:  A099348 A099349 A099350 * A099352 A099353 A099354

KEYWORD

nonn,more

AUTHOR

Brian Kell, Oct 12 2004

EXTENSIONS

a(13)-a(14) from Jinyuan Wang, Feb 04 2020

STATUS

approved

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Last modified March 6 03:35 EST 2021. Contains 341841 sequences. (Running on oeis4.)