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A288445
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Numbers k such that k!6 + 18 is prime, where k!6 is the sextuple factorial number (A085158 ).
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1
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1, 5, 11, 13, 17, 19, 23, 31, 37, 41, 49, 83, 115, 161, 205, 617, 683, 769, 799, 1117, 1151, 1685, 1697, 1951, 2173, 3619, 3647, 6229, 6463, 6613, 9827, 12985, 15721, 16933, 22579, 25181, 38869, 48755
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OFFSET
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1,2
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COMMENTS
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Corresponding primes are: 19, 23, 73, 109, 953, 1747, 21523, 1339993, 49579093, 894930593, ...
a(39) > 50000.
Terms > 49 correspond to probable primes.
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LINKS
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EXAMPLE
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11!6 + 18 = 11*5 + 18 = 73 is prime, so 11 is in the sequence.
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MATHEMATICA
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MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 18] &]
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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