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 A330068 #34 Feb 27 2020 05:57:28
%S A330068 1,3,4,12,84,3612,94116,4429004844,104990793204
%N A330068 Numbers k such that Sum_{i=1..k} i^A000010(k) == 2 (mod k).
%C A330068 Apparently includes the sequence 2*A054377.
%C A330068 Additional terms include 4429004844, 104990793204, and 16980843167119376821413542522172.
%C A330068 a(10) > 10^13. - _Giovanni Resta_, Feb 27 2020
%t A330068 G[n_, k_] := G[n, k] = Mod[Sum[PowerMod[i, k, n], {i, 1, n}], n];
%t A330068 Select[Range[2000], G[#, EulerPhi[#]] == 2 &]
%t A330068 fa=FactorInteger;
%t A330068 se[n_, k_] := Select[Transpose[fa[n]][[1]], IntegerQ[k/(# - 1)] &];
%t A330068 sumlis[li_] := Sum[li[[i]], {i, 1, Length[li]}]
%t A330068 Table[If[Mod[-n/se[n, EulerPhi[n]] // sumlis, n] == 2, n], {n, 1, 1000000}] // Union
%o A330068 (PARI) isok(n) = sumdiv(n, d, eulerphi(n/d) * Mod(d, n)^eulerphi(n)) == 2; \\ _Daniel Suteu_, Jan 13 2020
%Y A330068 Cf. A000010, A054377, A007850, A330069.
%K A330068 nonn,hard,more
%O A330068 1,2
%A A330068 _José María Grau Ribas_, Nov 30 2019
%E A330068 a(8)-a(9) from _Giovanni Resta_, Feb 27 2020