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 A076680 Numbers k such that 4*k! + 1 is prime. 11
 0, 1, 4, 7, 8, 9, 13, 16, 28, 54, 86, 129, 190, 351, 466, 697, 938, 1510, 2748, 2878, 3396, 4057, 4384, 5534 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(25) > 6311. - Jinyuan Wang, Feb 06 2020 LINKS Factor Database, Factors of the numbers 4z!+1 EXAMPLE k = 7 is a term because 4*7! + 1 = 20161 is prime. MATHEMATICA Select[Range[5000], PrimeQ[4#!+1]&] (* Harvey P. Dale, Mar 23 2011 *) PROG (PARI) is(k) = ispseudoprime(4*k!+1); \\ Jinyuan Wang, Feb 06 2020 CROSSREFS 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 KEYWORD nonn,more AUTHOR Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002 EXTENSIONS Corrected (added missed terms 2748, 2878) by Serge Batalov, Feb 24 2015 a(24) from Jinyuan Wang, Feb 06 2020 STATUS approved

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Last modified January 16 15:53 EST 2021. Contains 340206 sequences. (Running on oeis4.)