This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A258452 #18 Nov 10 2015 18:53:29 %S A258452 9,11,21,23,45,65,79,153,155,199,361,799,883,1237,1253,1753,4975,5117, %T A258452 5843,8179,12831 %N A258452 Numbers n such that n!! - 512 is prime. %C A258452 Corresponding primes are 433, 9883, 13749310063, 316234142713, ... . %C A258452 a(22) > 50000. %H A258452 Joe McLean, <a href="http://web.archive.org/web/20091027034731/http://uk.geocities.com/nassarawa%40btinternet.com/probprim2.htm">Interesting Sources of Probable Primes</a> %t A258452 Select[Range[0, 50000], If[#!! - 512 > 0, PrimeQ[#!! - 512]] &] %o A258452 (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 %Y A258452 Cf. A006882, A007749, A094144, A123910, A258616, A262772. %K A258452 hard,more,nonn %O A258452 1,1 %A A258452 _Robert Price_, Nov 05 2015