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 A248879 #11 Mar 10 2015 01:42:35 %S A248879 0,1,3,5,8,11,16,18,25,30,36,87,118,142,2789,3142,3557,3686,4190,7328 %N A248879 Numbers k >= 0 such that 2^k*(k+1)!+1 is prime. %C A248879 a(21) > 10^4. %e A248879 a(3) = 2^3*(3+1)!+1 = 193 which is prime. %t A248879 Select[Range[0,10000], PrimeQ[2^#*(#+1)!+1] &] %o A248879 (PARI) for(n=0,10^3,if(ispseudoprime((n+1)!*2^n+1),print1(n,", "))) \\ _Derek Orr_, Mar 06 2015 %Y A248879 Cf. A093154. %K A248879 nonn,more %O A248879 1,3 %A A248879 _Robert Price_, Mar 05 2015