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A099350
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Numbers k such that 4*k! - 1 is prime.
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11
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0, 1, 2, 3, 5, 6, 10, 11, 51, 63, 197, 313, 579, 1264, 2276, 2669, 4316, 4382
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OFFSET
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1,3
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COMMENTS
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a(19) > 4570. - Jinyuan Wang, Feb 04 2020
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LINKS
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Table of n, a(n) for n=1..18.
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EXAMPLE
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k = 5 is here because 4*5! - 1 = 479 is prime.
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MAPLE
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for n from 0 to 1000 do if isprime(4*n! - 1) then print(n) end if end do;
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MATHEMATICA
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For[n = 0, True, n++, If[PrimeQ[4 n! - 1], Print[n]]] (* Jean-François Alcover, Sep 23 2015 *)
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PROG
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(PARI) is_A099350(n)=ispseudoprime(n!*4-1) \\ M. F. Hasler, Sep 20 2015
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CROSSREFS
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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
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KEYWORD
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nonn,hard,more
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AUTHOR
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Brian Kell, Oct 12 2004
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EXTENSIONS
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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
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STATUS
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approved
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