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 A015909 #15 Jun 29 2023 19:07:26
%S A015909 1,1,3,3,5,2,7,7,9,4,11,3,13,6,3,15,17,8,19,4,21,10,23,8,25,12,27,3,
%T A015909 29,5,31,31,33,16,7,8,37,18,18,15,41,6,43,11,45,22,47,15,49,24,21,4,
%U A015909 53,26,22,7,57,28,59,15,61,30,63,63,65,2,67,16,69,5,71,8,73,36,18,8,77,12,79,15,81,40,83,20,15,42,12,32,89,9,7,23,93,46,38,32,97,48,99,24
%N A015909 a(n) = smallest k >= 1 such that n divides k^n + k.
%H A015909 Harvey P. Dale, <a href="/A015909/b015909.txt">Table of n, a(n) for n = 1..1000</a>
%t A015909 sk[n_]:=Module[{k=1},While[PowerMod[k,n,n]!=n-k,k++];k]; Array[sk,100] (* _Harvey P. Dale_, Jun 29 2023 *)
%Y A015909 Cf. A015908.
%K A015909 nonn
%O A015909 1,3
%A A015909 _Robert G. Wilson v_
%E A015909 Definition, offset, and data corrected. Thanks to _Harvey P. Dale_ for pointing out that something was wrong. - _N. J. A. Sloane_, Jun 29 2023