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A258452
Numbers n such that n!! - 512 is prime.
4
9, 11, 21, 23, 45, 65, 79, 153, 155, 199, 361, 799, 883, 1237, 1253, 1753, 4975, 5117, 5843, 8179, 12831
OFFSET
1,1
COMMENTS
Corresponding primes are 433, 9883, 13749310063, 316234142713, ... .
a(22) > 50000.
MATHEMATICA
Select[Range[0, 50000], If[#!! - 512 > 0, PrimeQ[#!! - 512]] &]
PROG
(PARI) for(n=1, 1e4, if (ispseudoprime(m=prod(k=0, (n-1)\2, n - 2*k) - 512), print1(n", "))) \\ Altug Alkan, Nov 06 2015
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Robert Price, Nov 05 2015
STATUS
approved