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A123910
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Numbers n such that n!!-4 is prime.
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0
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5, 7, 9, 11, 13, 15, 19, 25, 35, 79, 81, 105, 171, 243, 271, 295, 355, 523, 591, 1211, 3073, 11157
(list;
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listen;
history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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Corresponding primes of the form k!!-4 = a(n)!!-4 are {11, 101, 941, 10391, 135131, 2027021, 654729071, 7905853580621, 221643095476699771871, ...}.
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LINKS
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Table of n, a(n) for n=1..22.
Joe McLean, Interesting Sources of Probable Primes
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MATHEMATICA
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Do[f=n!!-4; If[PrimeQ[f], Print[{n, f}]], {n, 1, 355}]
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CROSSREFS
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Cf. A007749, A094144.
Sequence in context: A062545 A020735 A108144 * A024886 A083249 A077153
Adjacent sequences: A123907 A123908 A123909 * A123911 A123912 A123913
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk, Oct 28 2006
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EXTENSIONS
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More terms from Farideh Firoozbakht, Nov 19 2006
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008
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STATUS
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approved
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