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A329177
Numbers k such that k![4] - 256 is prime, where k![4] = A007662(k) = quadruple factorial.
0
15, 17, 19, 21, 23, 25, 33, 39, 41, 43, 53, 63, 67, 73, 157, 167, 181, 195, 221, 327, 363, 419, 849, 861, 1233, 1265, 1599, 2413, 2515, 4009, 8291, 8475, 10685, 13957, 17453, 18409, 19117, 22739, 33313, 37861, 59703, 64983, 80697
OFFSET
1,1
COMMENTS
a(44) > 10^5.
The first 5 primes associated with this sequence are: 3209, 9689, 65579, 208589, 1513949.
LINKS
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[1000], (x = MultiFactorial[#, 4] - 256; x > 0 && PrimeQ[x]) &]
Select[Range[10, 1600], PrimeQ[Times@@Range[#, 1, -4]-256]&] (* The program generates the first 27 terms of the sequence. To generate more, increase the second Range constant but the program may take a long time to run. *) (* Harvey P. Dale, Aug 01 2022 *)
CROSSREFS
Sequence in context: A077033 A043669 A043704 * A074748 A183981 A155111
KEYWORD
nonn
AUTHOR
Robert Price, Nov 07 2019
STATUS
approved