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A204663
Numbers n such that n!8 + 2 is prime.
8
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
OFFSET
1,3
COMMENTS
n!8 = A114800(n).
See also links in A156165.
For odd k, n!k +-2 is even for all n > k and thus cannot be prime.
a(60) > 50000. - Robert Price, Aug 19 2012
MATHEMATICA
Select[Range[0, 9999], PrimeQ[Product[# - 8i, {i, 0, Floor[(# - 2)/8]}] + 2] &] (* Indranil Ghosh, Mar 13 2017 *)
PROG
(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\8, n-8*i)+2)& print1(n", "))
KEYWORD
nonn,hard
AUTHOR
M. F. Hasler, Jan 17 2012
EXTENSIONS
a(39)-a(59) from Robert Price, Aug 19 2012
STATUS
approved