login
A328454
Numbers k such that k![4] - 4 is prime, where k![4] = A007662(k) = quadruple factorial.
0
7, 9, 11, 15, 17, 19, 39, 45, 57, 59, 63, 69, 81, 85, 127, 141, 149, 153, 163, 165, 201, 235, 259, 377, 457, 649, 815, 897, 1057, 1433, 1453, 1519, 1759, 3047, 3561, 4151, 7025, 11917, 11971, 15295, 18919, 19449, 20765, 70385, 71293
OFFSET
1,1
COMMENTS
a(46) > 10^5.
The first 6 primes associated with this sequence are: 17, 41, 227, 3461, 9941, 65831.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[1000], (x = MultiFactorial[#, 4] - 4; x > 0 && PrimeQ[x]) &]
CROSSREFS
Sequence in context: A024828 A139058 A242103 * A254937 A222947 A107226
KEYWORD
nonn
AUTHOR
Robert Price, Nov 06 2019
STATUS
approved