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 A373031 #6 May 21 2024 05:30:47
%S A373031 1,1,1,-3,1,-3,1,-3,10,-3,1,6,1,-3,10,-19,1,6,1,-19,10,-3,1,-10,26,-3,
%T A373031 10,-19,1,31,1,-19,10,-3,26,-46,1,-3,10,6,1,-30,1,-19,35,-3,1,-46,50,
%U A373031 22,10,-19,1,-30,26,30,10,-3,1,-21,1,-3,59,-83,26,-30,1,-19,10,71
%N A373031 Expansion of Sum_{k>=1} (-1)^(k+1) * k^2 * x^(k^2) / (1 - x^k).
%F A373031 a(n) = Sum_{d|n, d <= sqrt(n)} (-1)^(d+1) * d^2.
%t A373031 nmax = 70; CoefficientList[Series[Sum[(-1)^(k + 1) k^2 x^(k^2)/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%Y A373031 Cf. A038548, A064027, A066839, A095118, A321543, A333781, A333782, A344300, A372625, A373032.
%K A373031 sign
%O A373031 1,4
%A A373031 _Ilya Gutkovskiy_, May 20 2024