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A076133
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Numbers k such that 2*k! - 1 is prime.
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11
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2, 3, 4, 5, 6, 7, 14, 15, 17, 22, 28, 91, 253, 257, 298, 659, 832, 866, 1849, 2495, 2716, 2773, 2831, 3364, 5264, 7429, 28539, 32123, 37868
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..29.
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EXAMPLE
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k = 5 is here because 2*5! - 1 = 239 is prime.
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MATHEMATICA
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Select[Range[8000], PrimeQ[2 #! - 1] &] (* Vincenzo Librandi, Feb 20 2015 *)
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PROG
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(MAGMA) [n: n in [1..600] | IsPrime(2*Factorial(n)-1)]; // Vincenzo Librandi, Feb 20 2015
(PARI) is(k) = ispseudoprime(2*k!-1); \\ Jinyuan Wang, Feb 04 2020
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CROSSREFS
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Cf. A051915.
Cf. A002982, A076134, A099350, A099351, A180627, A180628, A180629, A180630, A180631.
Sequence in context: A319723 A271377 A066336 * A277908 A032862 A032886
Adjacent sequences: A076130 A076131 A076132 * A076134 A076135 A076136
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KEYWORD
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nonn,more
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AUTHOR
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Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 30 2002
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EXTENSIONS
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a(24)-a(29) from Serge Batalov, Feb 18 2015
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STATUS
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approved
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