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 A229209 #16 Feb 19 2021 05:02:49
%S A229209 1,2,5,7,11,39,126,266,683,2514,12929
%N A229209 Numbers k such that Sum_{j=1..k} phi(j)^j == 0 (mod k).
%C A229209 Tested up to k = 600000. - _Jinyuan Wang_, Feb 19 2021
%e A229209 phi(1)^1 + phi(2)^2 + phi(3)^3 + phi(4)^4 + phi(5)^5 = 1^1 + 1^2 + 2^3 + 2^4 + 4^5 = 1050 and 1050/5 = 210.
%p A229209 with(numtheory); P:=proc(q) local n, t; t:=0;
%p A229209 for n from 1 to q do t:=t+phi(n)^n; if t mod n=0 then print(n);
%p A229209 fi; od; end: P(10^6);
%o A229209 (PARI) is(k) = sum(i=1, k, Mod(eulerphi(i), k)^i) == 0; \\ _Jinyuan Wang_, Feb 19 2021
%Y A229209 Cf. A000010, A227427, A227429, A227502, A227848, A229095, A229207, A229208, A229210, A229211.
%K A229209 nonn,more
%O A229209 1,2
%A A229209 _Paolo P. Lava_, Sep 16 2013