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A180626 Numbers k such that 9*k! + 1 is prime. 9
2, 6, 7, 10, 13, 15, 24, 29, 33, 44, 98, 300, 548, 942, 1099, 1176, 1632, 1794, 3676, 3768, 4804 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Tested to 4500. - Robert G. Wilson v, Sep 28 2010

a(22) > 5235. - Jinyuan Wang, Feb 05 2020

LINKS

Table of n, a(n) for n=1..21.

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

MATHEMATICA

fQ[n_] := PrimeQ[9 n! + 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst

PROG

(PARI) is(k) = ispseudoprime(9*k!+1); \\ Jinyuan Wang, Feb 05 2020

CROSSREFS

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A126896.

Sequence in context: A074223 A029459 A014862 * A061943 A029507 A047552

Adjacent sequences:  A180623 A180624 A180625 * A180627 A180628 A180629

KEYWORD

nonn,more

AUTHOR

Robert G. Wilson v, Sep 13 2010

EXTENSIONS

a(17)-a(20) from Robert G. Wilson v, Sep 28 2010

a(21) from Jinyuan Wang, Feb 05 2020

STATUS

approved

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Last modified July 15 04:34 EDT 2020. Contains 335763 sequences. (Running on oeis4.)