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 A113517 #3 Mar 30 2012 17:22:41
%S A113517 2,2,3,2,3,2,0,3,4,4,4,2,0,5,18,2,12,2,0,7,3,11,13,7,0,167,15,6,63,2,
%T A113517 0,7,6,21,49,3,0,27,30,3,22,106,0,10,30,4,294,7,0,32,19,6,7,41,0,21,4,
%U A113517 14,34,2,0,12,13,6,147,37,0,14,139,22,46,179,0,4,75,69,15,11,0,5,211,130
%N A113517 Least k such that k^n-k+1 is prime, or 0 if there is no such k.
%C A113517 a(n) is 0 for n=8,14,20,... (n=2 mod 6) because, for those n, the polynomial x^n-x+1 has the factor x^2-x+1. Using a result of Selmer, it can be shown that x^n-x+1 is irreducible for all other n. Does a(n) exist for all n>1?
%t A113517 Table[f=FactorList[x^n-x+1]; If[Length[f]>2, k=0, k=1; While[ !PrimeQ[k^n-k+1], k++ ]]; k, {n, 2, 100}]
%Y A113517 Cf. A113516 (smallest k such that n^k-n+1 is prime).
%K A113517 nonn
%O A113517 2,1
%A A113517 _T. D. Noe_, Jan 12 2006