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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
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.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[2, 50000], PrimeQ[MultiFactorial[#, 4] - 2] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Price, Mar 10 2017
EXTENSIONS
a(43)-a(44) from Robert Price, Jul 24 2017
STATUS
approved