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A204663
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Numbers n such that n!8 + 2 is prime.
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8
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0, 1, 3, 5, 9, 13, 15, 21, 23, 27, 33, 35, 45, 53, 55, 57, 75, 79, 109, 197, 221, 227, 267, 333, 413, 545, 695, 703, 801, 967, 1029, 1329, 1351, 1475, 1549, 1757, 2173, 2861, 3161, 3167, 3885, 4681, 4965, 6277, 6655, 8477, 9821, 9959, 10269, 17999, 23349, 29347, 29477, 30181, 34133, 36687, 40985, 43395, 47499
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OFFSET
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1,3
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COMMENTS
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For odd k, n!k +-2 is even for all n > k and thus cannot be prime.
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LINKS
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MATHEMATICA
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Select[Range[0, 9999], PrimeQ[Product[# - 8i, {i, 0, Floor[(# - 2)/8]}] + 2] &] (* Indranil Ghosh, Mar 13 2017 *)
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PROG
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(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\8, n-8*i)+2)& print1(n", "))
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CROSSREFS
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Cf. A204657, A204658, A204659, A204660, A204661, A204662, A204664, A156165, A156167, A085150, A085148, A085146, A037083, A080778, A002981.
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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