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A283559
Numbers k such that k![10]-2 is prime, where k![10] is the ten-fold multifactorial.
1
4, 5, 7, 9, 13, 15, 21, 25, 29, 31, 33, 41, 45, 49, 77, 195, 197, 199, 211, 309, 319, 345, 349, 395, 509, 533, 539, 597, 615, 705, 781, 803, 869, 969, 1313, 1317, 1331, 1335, 1337, 1429, 1597, 2121, 2133, 2513, 2547, 2733, 2885, 2931, 3701, 3709, 4681, 5911, 5933, 6125, 8191, 10637, 10679, 10845, 14901, 15629, 17165, 21691, 21867, 23119, 27033, 28601, 31245, 31957, 33289, 35773, 45011, 51079, 63241, 81369, 92615
OFFSET
1,1
COMMENTS
a(76) > 50000.
The first 13 primes associated with this sequence: 2, 3, 5, 7, 37, 73, 229, 1873, 4957, 7159, 29599, 293599, 2953123.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[2, 50000], PrimeQ[MultiFactorial[#, 10] - 2] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Price, Mar 10 2017
EXTENSIONS
a(72)-a(75) from Robert Price, Apr 03 2017
STATUS
approved