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A178488
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Numbers k such that 8*k! + 1 is prime.
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9
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2, 4, 9, 10, 11, 12, 15, 25, 31, 46, 53, 78, 318, 615, 955, 1646, 2669, 2672, 3515
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OFFSET
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1,1
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COMMENTS
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a(20) > 3810. - Jinyuan Wang, Feb 05 2020
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LINKS
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Table of n, a(n) for n=1..19.
Index entries for sequences related to numbers of primes of the form k*n!+-1
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MATHEMATICA
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fQ[n_] := PrimeQ[8 n! + 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst
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PROG
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(PARI) for(k=1, 999, ispseudoprime(8*k!+1) & print1(k, ", "))
(PFGW) ABC2 8*$a!+1
a: from 1 to 1000 // Jinyuan Wang, Feb 05 2020
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CROSSREFS
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Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A180626, A126896.
Sequence in context: A275658 A267414 A072583 * A226821 A047465 A002258
Adjacent sequences: A178485 A178486 A178487 * A178489 A178490 A178491
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KEYWORD
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nonn,hard,more
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AUTHOR
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Robert G. Wilson v, Sep 13 2010 and M. F. Hasler, Sep 16 2010
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EXTENSIONS
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a(16)-a(19) from Jinyuan Wang, Feb 05 2020
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STATUS
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approved
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