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A329112
Numbers k such that k![4] - 8 is prime, where k![4] = A007662(k) = quadruple factorial.
0
7, 9, 11, 13, 15, 19, 21, 23, 29, 35, 37, 55, 57, 77, 85, 139, 243, 251, 433, 667, 671, 895, 2127, 2263, 2293, 2645, 2733, 2845, 3675, 4381, 6453, 6825, 36557, 78531
OFFSET
1,1
COMMENTS
a(35) > 10^5.
The first 6 primes associated with this sequence are: 13, 37, 223, 577, 3457, 65827.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[1000], (x = MultiFactorial[#, 4] - 8; x > 0 && PrimeQ[x]) &]
CROSSREFS
Sequence in context: A059808 A020742 A193071 * A347886 A023389 A248963
KEYWORD
nonn
AUTHOR
Robert Price, Nov 06 2019
STATUS
approved