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 A156167 Numbers n such that n![7]-1 is prime (where n![7] = A114799(n) = septuple factorial). 10
 3, 4, 6, 8, 9, 10, 11, 12, 14, 17, 20, 24, 30, 31, 32, 46, 52, 54, 59, 98, 104, 143, 145, 160, 174, 198, 199, 202, 212, 215, 254, 371, 382, 452, 674, 739, 959, 1249, 1657, 2291, 2553, 2650, 3562, 3727, 3853, 4389, 4604, 5449, 5659, 6026, 6878, 7900, 9564, 10150, 12444, 13321, 22642, 24014, 26598, 27430, 31386, 40707, 43328, 45811 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(65) > 50000. - Robert Price, Sep 09 2012 LINKS C. Caldwell, H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75 Ken Davis, Status of Search for Multifactorial Primes.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 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]]; Select[Range[0, 1000], PrimeQ[MultiFactorial[#, 7] - 1] & ] (* Robert Price, Apr 19 2019 *) PROG (PARI) mf(n, k=7)=prod(i=0, (n-2)\k, n-i*k) for( n=1, 9999, ispseudoprime(mf(n)-1) & print1(n", ")) CROSSREFS cf. A156165, A051592, A085149, A085147, A084438, A007749, A002982. Sequence in context: A325209 A121543 A080702 * A090864 A118300 A263098 Adjacent sequences:  A156164 A156165 A156166 * A156168 A156169 A156170 KEYWORD nonn AUTHOR M. F. Hasler, Feb 10 2009 EXTENSIONS a(43)-a(64) from Robert Price, Sep 09 2012 STATUS approved

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Last modified April 22 19:11 EDT 2021. Contains 343177 sequences. (Running on oeis4.)