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A076680
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Numbers k such that 4*k! + 1 is prime.
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11
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0, 1, 4, 7, 8, 9, 13, 16, 28, 54, 86, 129, 190, 351, 466, 697, 938, 1510, 2748, 2878, 3396, 4057, 4384, 5534
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OFFSET
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1,3
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COMMENTS
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a(25) > 6311. - Jinyuan Wang, Feb 06 2020
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LINKS
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Table of n, a(n) for n=1..24.
Factor Database, Factors of the numbers 4z!+1
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EXAMPLE
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k = 7 is a term because 4*7! + 1 = 20161 is prime.
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MATHEMATICA
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Select[Range[5000], PrimeQ[4#!+1]&] (* Harvey P. Dale, Mar 23 2011 *)
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PROG
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(PARI) is(k) = ispseudoprime(4*k!+1); \\ Jinyuan Wang, Feb 06 2020
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CROSSREFS
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Cf. m*n!-1 is a prime: A076133, A076134, A099350, A099351, A180627-A180631.
Cf. m*n!+1 is a prime: A051915, A076679-A076683, A178488, A180626, A126896.
Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199-A139205.
Cf. n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071.
Sequence in context: A074231 A310938 A289631 * A235623 A001074 A214206
Adjacent sequences: A076677 A076678 A076679 * A076681 A076682 A076683
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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 25 2002
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EXTENSIONS
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Corrected (added missed terms 2748, 2878) by Serge Batalov, Feb 24 2015
a(24) from Jinyuan Wang, Feb 06 2020
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STATUS
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approved
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