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 A305320 #19 Jun 01 2018 10:42:50
%S A305320 1,-1,0,-1,0,1,-1,1,-1,2,1,0,-3,0,0,2,1,-2,0,1,2,-1,-3,-4,0,3,4,0,-4,
%T A305320 -1,6,-3,3,-9,0,5,10,0,-6,-7,0,6,-2,2,-9,6,7,4,-7,-7,-11,8,11,3,-5,-1,
%U A305320 -3,9,-10,1,-9,0,16,8,0,-4,-4,-20,12,-8,11,0,-7,14,-2
%N A305320 Expansion of Product_{k>=1} (1 - x^sigma(k)).
%H A305320 Seiichi Manyama, <a href="/A305320/b305320.txt">Table of n, a(n) for n = 0..1000</a>
%p A305320 with(numtheory):
%p A305320 seq(coeff(series(mul(1-x^sigma(k),k=1..n), x,90),x,n),n=0..80); # _Muniru A Asiru_, May 31 2018
%o A305320 (PARI) N=99; x='x+O('x^N); Vec(prod(k=1, N, 1-x^sigma(k)))
%Y A305320 Cf. A000203, A111865, A305321.
%K A305320 sign
%O A305320 0,10
%A A305320 _Seiichi Manyama_, May 30 2018