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 A099350 Numbers k such that 4*k! - 1 is prime. 11
 0, 1, 2, 3, 5, 6, 10, 11, 51, 63, 197, 313, 579, 1264, 2276, 2669, 4316, 4382 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(19) > 4570. - Jinyuan Wang, Feb 04 2020 LINKS EXAMPLE k = 5 is here because 4*5! - 1 = 479 is prime. MAPLE for n from 0 to 1000 do if isprime(4*n! - 1) then print(n) end if end do; MATHEMATICA For[n = 0, True, n++, If[PrimeQ[4 n! - 1], Print[n]]] (* Jean-François Alcover, Sep 23 2015 *) PROG (PARI) is_A099350(n)=ispseudoprime(n!*4-1) \\ M. F. Hasler, Sep 20 2015 CROSSREFS Cf. A076680. Cf. A002982, A076133, A076134, A099351, A180627, A180628, A180629, A180630, A180631. Sequence in context: A057546 A339514 A138587 * A337218 A306296 A191173 Adjacent sequences:  A099347 A099348 A099349 * A099351 A099352 A099353 KEYWORD nonn,hard,more AUTHOR Brian Kell, Oct 12 2004 EXTENSIONS a(14) from Alois P. Heinz, Sep 21 2015 a(15)-a(16) from Jean-François Alcover, Sep 23 2015 a(17)-a(18) from Jinyuan Wang, Feb 04 2020 STATUS approved

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Last modified May 5 17:04 EDT 2021. Contains 343572 sequences. (Running on oeis4.)