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 A341436 #28 Jul 31 2025 06:57:04
%S A341436 1,5,16,208,688,784,2864,9555,17776,81239
%N A341436 Numbers k such that k divides Sum_{j=1..k} j^(k+1-j).
%C A341436 Numbers k such that k divides A003101(k).
%C A341436 a(11) > 10^5.
%H A341436 Mathematics Stack Exchange, <a href="https://math.stackexchange.com/questions/454585/is-it-true-that-if-p-neq5-is-a-prime-number-then-1p2p-1-cdotsp-12p">Is it true that if p != 5 is a prime number then 1^p + 2^(p-1) + ... + (p-1)^2 + p^1 != 0 (mod p)?</a>.
%e A341436 1^5 + 2^4 + 3^3 + 4^2 + 5^1 = 65 = 5 * 13. So 5 is a term.
%t A341436 Do[If[Mod[Sum[PowerMod[k, n + 1 - k, n], {k, 1, n}], n] == 0, Print[n]], {n, 1, 3000}] (* _Vaclav Kotesovec_, Feb 12 2021 *)
%o A341436 (PARI) isok(n) = sum(k=1, n, Mod(k, n)^(n+1-k))==0;
%Y A341436 Cf. A003101, A128981, A188775, A341437.
%K A341436 nonn,more
%O A341436 1,2
%A A341436 _Seiichi Manyama_, Feb 11 2021