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 A333502 #11 Mar 24 2020 22:31:07
%S A333502 1,0,4,903,12,776119592182705,12,42931441,136,27486820443,60,
%T A333502 107342336783,84
%N A333502 a(n) is the n-th number m such that m^2 divides n^m - 1 (or 0 if m does not exist).
%F A333502 a(n) = A333500(n,n).
%o A333502 (PARI) {a(n) = if(n==2, 0, my(cnt=0, k=0); while(cnt<n, k++; if(Mod(n, k^2)^k==1, cnt++)); k)}
%Y A333502 Main diagonal of A333500.
%Y A333502 Cf. A127106, A127100, A128405, A333433.
%K A333502 nonn,more
%O A333502 1,3
%A A333502 _Seiichi Manyama_, Mar 24 2020