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 A291344 Numbers k such that k!4 + 2^4 is prime, where k!4 = k!!!! is the quadruple factorial number (A007662). 1
 0, 1, 3, 7, 9, 13, 19, 27, 35, 37, 65, 67, 75, 83, 89, 101, 111, 229, 363, 633, 1605, 1663, 1769, 1863, 1947, 2695, 3003, 5309, 7835, 9495, 9945, 11041, 18833, 21119, 21465, 21889, 24509, 26757, 27595, 33657, 54007, 67699, 87915 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Corresponding primes are: 17, 17, 19, 37, 61, 601, 65851, 40883551, ... a(44) > 10^5. Terms > 37 correspond to probable primes. LINKS Table of n, a(n) for n=1..43. Henri & Renaud Lifchitz, PRP Records. Search for n!4+16. Joe McLean, Interesting Sources of Probable Primes OpenPFGW Project, Primality Tester EXAMPLE 13!4 + 2^4 = 13*9*5*1 + 16 = 601 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] + 2^4] &] CROSSREFS Cf. A007662, A037082, A084438, A123910, A242994. Sequence in context: A364614 A215800 A103601 * A297002 A111250 A118643 Adjacent sequences: A291341 A291342 A291343 * A291345 A291346 A291347 KEYWORD nonn,more AUTHOR Robert Price, Aug 22 2017 EXTENSIONS a(41)-a(43) from Robert Price, Sep 25 2019 STATUS approved

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Last modified August 12 23:28 EDT 2024. Contains 375113 sequences. (Running on oeis4.)