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 A359658 #11 Jan 10 2023 06:44:13
%S A359658 0,1,3,12,118,3345,337337,117813304,182877273548,1095343802746641,
%T A359658 33833602932485958015,4588786457956655542361532,
%U A359658 3347980595386754115503487966082,13023291362471615806961306534915589217
%N A359658 a(n) = Sum_{k=0..n} k^(k * (n-k) + 1).
%F A359658 G.f.: Sum_{k>=0} k * x^k/(1 - k^k * x).
%o A359658 (PARI) a(n) = sum(k=0, n, k^(k*(n-k)+1));
%o A359658 (PARI) my(N=20, x='x+O('x^N)); concat(0, Vec(sum(k=0, N, k*x^k/(1-k^k*x))))
%Y A359658 Cf. A349893, A359659.
%K A359658 nonn
%O A359658 0,3
%A A359658 _Seiichi Manyama_, Jan 10 2023