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 A075757 #8 Jun 24 2014 01:08:26 %S A075757 1,2,3,3,3,3,8,7,10,9,17,7,9,8,19,7,11,11,15,15,11,14,7,20,31,13,7,0, %T A075757 13,0,25,20,7,23,23,21,7,19,21,0,52,7,23,13,13,17,50,8,76,19,51,41,7, %U A075757 107,57,27,55,0,55,0,27,29,0,79,0,45,61,48,55,39,80,56,153,76,0,35,11 %N A075757 Smallest positive integer k such that n!+k!+1 is prime, or 0 if no such k exists. %e A075757 3!=6, 6+1!+1=8, 6+2!+1=9, 6+3!+1=13, which is prime, so a(3)=3. %t A075757 a[1]=1; a[n_] := For[k=2, True, k++, If[Mod[n!+1, k]==0, Return[0]]; If[ProvablePrimeQ[n!+k!+1], Return[k]]] (* First do <<NumberTheory`PrimeQ` *) %K A075757 nonn %O A075757 1,2 %A A075757 _Jon Perry_, Oct 08 2002 %E A075757 Edited by _Dean Hickerson_, Oct 10 2002 %E A075757 The fact that 73!+153!+1 is prime, so a(73)=153, was proved, using Primo, by _Robert G. Wilson v_, Oct 16 2002