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 A319669 #11 Dec 30 2023 12:36:59
%S A319669 1,-1,-3,-2,1,10,13,15,-1,-30,-63,-89,-80,-14,131,304,493,561,434,-32,
%T A319669 -836,-1895,-2960,-3583,-3240,-1338,2401,8004,14499,20494,23369,20401,
%U A319669 8567,-13741,-46408,-85717,-124027,-149612,-147167,-101002,2520,168026,388077,634914
%N A319669 Expansion of Product_{k>=1} (1 - x^k)^(2*k-1).
%F A319669 G.f.: exp(Sum_{k>=1} (sigma_1(k) - 2*sigma_2(k))*x^k/k).
%p A319669 a:=series(mul((1-x^k)^(2*k-1),k=1..100),x=0,44): seq(coeff(a,x,n),n=0..43); # _Paolo P. Lava_, Apr 02 2019
%t A319669 nmax = 43; CoefficientList[Series[Product[(1 - x^k)^(2 k - 1), {k, 1, nmax}], {x, 0, nmax}], x]
%t A319669 nmax = 43; CoefficientList[Series[Exp[Sum[(DivisorSigma[1, k] - 2 DivisorSigma[2, k]) x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x]
%t A319669 a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d (1 - 2 d), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 43}]
%Y A319669 Cf. A000203, A001157, A073592, A253289, A255835, A276551, A278945, A285069.
%K A319669 sign
%O A319669 0,3
%A A319669 _Ilya Gutkovskiy_, Sep 25 2018