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 A156165 Numbers k such that k![7]+1 is prime (n![7] = A114799(n) = septuple factorial). 11
 0, 1, 2, 4, 6, 9, 10, 12, 13, 24, 25, 26, 29, 31, 35, 36, 47, 49, 57, 58, 64, 71, 73, 75, 78, 80, 97, 123, 125, 129, 131, 135, 147, 150, 159, 183, 201, 250, 251, 255, 298, 336, 337, 458, 467, 556, 570, 657, 743, 801, 908, 925, 1003, 1209, 1473, 1524, 1716, 1881, 1926 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(103) > 50000. - Robert Price, Sep 03 2012 LINKS Robert Price, Table of n, a(n) for n = 1..102 C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75 Ken Davis, Status of Search for Multifactorial Primes. Ken Davis, Results for n!7+1. MATHEMATICA mf[n_, k_] := Product[n - i k, {i, 0, Quotient[n - 2, k]}]; Reap[For[k = 0, k <= 2000, k++, If[PrimeQ[mf[k, 7] + 1], Sow[k]]]][[2, 1]] (* Jean-François Alcover, Feb 26 2019 *) PROG (PARI) mf(n, k=7)=prod(i=0, (n-2)\k, n-i*k) for( n=0, 9999, ispseudoprime(mf(n)+1) & print1(n", ")) CROSSREFS Cf. A156167, A085150, A085148, A085146, A037083, A080778, A002981. Sequence in context: A162202 A210380 A228359 * A024968 A047411 A288623 Adjacent sequences:  A156162 A156163 A156164 * A156166 A156167 A156168 KEYWORD nonn AUTHOR M. F. Hasler, Feb 10 2009 STATUS approved

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Last modified February 26 05:51 EST 2020. Contains 332277 sequences. (Running on oeis4.)