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 A308290 #8 Aug 10 2019 04:26:57
%S A308290 1,2,3,1,-1,-6,-3,2,9,9,-6,-24,-25,16,72,75,-35,-213,-239,78,627,767,
%T A308290 -182,-1890,-2477,355,5847,8109,-360,-18195,-26801,-1225,56724,89040,
%U A308290 11431,-177897,-297030,-61857,560310,994427,284075,-1766754,-3338212,-1201932
%N A308290 Expansion of Sum_{k>=1} mu(k)*log(1 + x^k/(1 - x^k)^3)/k.
%C A308290 Inverse Euler transform of triangular numbers (A000217).
%F A308290 -1 + Product_{n>=1} 1/(1 - x^n)^a(n) = g.f. of A000217.
%t A308290 nmax = 44; CoefficientList[Series[Sum[MoebiusMu[k] Log[1 + x^k/(1 - x^k)^3]/k, {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%t A308290 nmax = 50; s = ConstantArray[0, nmax]; Do[s[[j]] = j^2*(j + 1)/2 - Sum[s[[d]]*(j - d)*(j - d + 1)/2, {d, 1, j - 1}], {j, 1, nmax}]; Table[Sum[MoebiusMu[k/d]*s[[d]], {d, Divisors[k]}]/k, {k, 1, nmax}] (* _Vaclav Kotesovec_, Aug 10 2019 *)
%Y A308290 Cf. A000217, A000294, A008683, A308291, A316152.
%K A308290 sign
%O A308290 1,2
%A A308290 _Ilya Gutkovskiy_, May 18 2019