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 A015908 #23 Jun 29 2023 15:38:41
%S A015908 1,0,0,15,0,1565,111,35,0,123,365,671,15,185653,259,85,0,4369,39,247,
%T A015908 800005,39,55,115,1731,85,221,135,35,105821,51,403,0,55,1649,1939,
%U A015908 3177,3293,95,2283,3845,697,357,215,143,153,667,235,435,511,485
%N A015908 Smallest odd k>n such that k | n^k + n, or 0 if n=2^m.
%H A015908 Sean A. Irvine, <a href="/A015908/b015908.txt">Table of n, a(n) for n = 0..136</a>
%t A015908 fk[n_]:=Module[{k=n+1},If[EvenQ[k],k++];If[IntegerQ[Log[2,n]], k=0, While[ Mod[ n^k+n,k]!=0,k+=2]];k]; Array[fk,60,0] (* _Harvey P. Dale_, Mar 12 2019 *)
%o A015908 (PARI) isp2(n) = (n==1) || (n==2) || (isprimepower(n, &p) && (p==2));
%o A015908 a(n) = {if (isp2(n), return (0)); my(k = if (n%2, n+2, n+1)); while(lift(Mod(n,k)^k + Mod(n,k)), k+=2); k;} \\ _Michel Marcus_, Dec 19 2018
%Y A015908 Cf. A015906 (without restriction on the parity of k).
%K A015908 nonn
%O A015908 0,4
%A A015908 _Robert G. Wilson v_
%E A015908 Missing a(0)=1, a(1)=0 inserted and a(5) corrected by _Sean A. Irvine_, Dec 19 2018