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A180628
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Numbers k such that 7*k! - 1 is prime.
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8
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2, 3, 4, 5, 6, 7, 8, 12, 23, 25, 31, 57, 74, 86, 140, 240, 310, 703, 713, 796, 1028, 1102, 1924
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history;
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OFFSET
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1,1
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COMMENTS
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a(24) > 2589. - Jinyuan Wang, Feb 03 2020
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LINKS
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Table of n, a(n) for n=1..23.
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[7 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) is(k) = ispseudoprime(7*k!-1); \\ Jinyuan Wang, Feb 03 2020
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CROSSREFS
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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
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KEYWORD
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nonn,more
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AUTHOR
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Robert G. Wilson v, Sep 13 2010
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EXTENSIONS
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a(23) from Jinyuan Wang, Feb 03 2020
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STATUS
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approved
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