A258452 Numbers n such that n!! - 512 is prime.

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.

Links

Table of n, a(n) for n=1..21.

Joe McLean, Interesting Sources of Probable Primes

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

Cf. A006882, A007749, A094144, A123910, A258616, A262772.

Sequence in context: A284294 A195572 A046259 * A299250 A074345 A022323

Adjacent sequences: A258449 A258450 A258451 * A258453 A258454 A258455

Keyword

hard,more,nonn

Author

Robert Price, Nov 05 2015

Status

approved