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 A308671 #16 May 11 2021 01:54:27
%S A308671 1,17,19684,4294967313,298023223876953126,
%T A308671 10314424798490535546171968756,
%U A308671 256923577521058878088611477224235621321608,6277101735386680763835789423207666416102355444468329480209
%N A308671 a(n) = Sum_{d|n} d^(d^2).
%F A308671 L.g.f.: -log(Product_{k>=1} (1 - x^k)^(k^(k^2-1))) = Sum_{k>=1} a(k)*x^k/k.
%t A308671 a[n_] := DivisorSum[n, #^(#^2) &]; Array[a, 8] (* _Amiram Eldar_, May 11 2021 *)
%o A308671 (PARI) {a(n) = sumdiv(n, d, d^d^2)}
%o A308671 (PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-x^k)^(k^(k^2-1))))))
%Y A308671 Column k=2 of A308674.
%Y A308671 Cf. A000005, A062796, A308670.
%K A308671 nonn
%O A308671 1,2
%A A308671 _Seiichi Manyama_, Jun 16 2019