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 A283554 Numbers k such that k![4] - 2 is prime, where k![4] = A007662(k) = quadruple factorial. 1
 4, 5, 7, 9, 11, 15, 21, 25, 29, 49, 79, 87, 95, 125, 133, 153, 157, 185, 201, 217, 223, 289, 323, 469, 533, 567, 821, 1001, 1999, 2523, 2533, 2827, 2843, 4821, 8153, 8947, 12739, 19353, 22929, 30629, 31809, 37785, 74913, 97411 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(45) > 10^5. The first 9 primes associated with this sequence: 2, 3, 19, 43, 229, 3463, 208843, 5221123, 151412623. LINKS C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75 Ken Davis, Status of Search for Multifactorial Primes. MATHEMATICA MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]]; Select[Range[2, 50000], PrimeQ[MultiFactorial[#, 4] - 2] &] CROSSREFS Cf. A076185, A085158, A094144, A204657. Sequence in context: A267087 A050560 A204664 * A035243 A035255 A335984 Adjacent sequences:  A283551 A283552 A283553 * A283555 A283556 A283557 KEYWORD nonn AUTHOR Robert Price, Mar 10 2017 EXTENSIONS a(43)-a(44) from Robert Price, Jul 24 2017 STATUS approved

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Last modified December 2 10:39 EST 2020. Contains 338876 sequences. (Running on oeis4.)