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 A291343 Numbers k such that k!4 + 2^3 is prime, where k!4 = k!!!! is the quadruple factorial number (A007662). 1
 3, 5, 7, 9, 11, 13, 19, 23, 25, 33, 39, 41, 63, 67, 71, 85, 87, 91, 133, 171, 243, 291, 1239, 1543, 1879, 2169, 2421, 3149, 3323, 3377, 3501, 3529, 5433, 5599, 7299, 11227, 11275, 13939, 27147, 32435, 86455, 92105 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Corresponding primes are: 11, 13, 29, 53, 239, 593, 65843, 1514213, 5221133, ... a(43) > 10^5. Terms > 33 correspond to probable primes. LINKS Henri & Renaud Lifchitz, PRP Records. Search for n!4+8. Joe McLean, Interesting Sources of Probable Primes OpenPFGW Project, Primality Tester EXAMPLE 13!4 + 2^3 = 13*9*5*1 + 8 = 593 is prime, so 13 is in the sequence. MATHEMATICA MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]]; Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 4] + 2^3] &] CROSSREFS Cf. A007662, A037082, A084438, A123910, A242994. Sequence in context: A309361 A133854 A239008 * A030155 A143448 A226484 Adjacent sequences:  A291340 A291341 A291342 * A291344 A291345 A291346 KEYWORD nonn,more AUTHOR Robert Price, Aug 22 2017 EXTENSIONS a(41)-a(42) from Robert Price, Sep 25 2019 STATUS approved

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Last modified May 6 03:38 EDT 2021. Contains 343580 sequences. (Running on oeis4.)