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A284190
Numbers k such that k![14]-2 is prime, where k![14] is the fourteen-fold multifactorial.
2
4, 5, 7, 9, 13, 15, 27, 29, 31, 39, 41, 45, 59, 61, 75, 83, 87, 107, 123, 153, 159, 229, 255, 333, 343, 381, 399, 469, 599, 671, 707, 735, 737, 745, 797, 981, 1115, 1121, 1233, 1545, 1625, 1943, 2177, 2355, 2593, 2875, 2891, 6779, 6937, 7717, 7767, 9947, 12285, 13411, 15367, 15457, 15699, 17319, 18035, 20617, 33125, 37449, 56353, 61869, 80599
OFFSET
1,1
COMMENTS
a(66) > 100000.
The first 12 primes associated with this sequence: 2, 3, 5, 7, 11, 13, 349, 433, 1579, 10723, 14389, 71143.
k![14](0..20) = 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 32, 51, 72, 95, 120.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[2, 100000], PrimeQ[MultiFactorial[#, 14] - 2] &]
PROG
(PARI) M(n, k) = if(n<1, 1, n*M(n - k, k));
isok(n) = isprime(M(n, 14) - 2); \\ Indranil Ghosh, Mar 22 2017
CROSSREFS
Sequence in context: A052147 A139690 A283559 * A035266 A035264 A234257
KEYWORD
nonn
AUTHOR
Robert Price, Mar 22 2017
STATUS
approved