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A051592
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Numbers k such that k!!!!!! - 1 is prime.
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3
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3, 4, 6, 12, 14, 54, 74, 102, 114, 302, 318, 366, 614, 1178, 1188, 3110, 7284, 21432, 21906, 25848, 29882, 38618, 41990, 84510, 86022
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OFFSET
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1,1
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COMMENTS
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k!!!!!! = k*(k-6)*(k-12)*(k-18)*...
The search for multifactorial primes started by Ray Ballinger is now continued by a team of volunteers on the website of Ken Davis (see link).
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LINKS
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MATHEMATICA
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MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 1000], PrimeQ[MultiFactorial[#, 6] - 1] & ] (* Robert Price, Apr 19 2019 *)
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CROSSREFS
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KEYWORD
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hard,nonn
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AUTHOR
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EXTENSIONS
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Corrected and extended by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008
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STATUS
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approved
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