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 A281590 #12 Apr 15 2017 09:47:06
%S A281590 1,4,9,15,20,27,33,41,48,56,64,72,80,89,98,107,116,126,136,146,156,
%T A281590 166,176,187,198,208,219,231,242,253,265,276,288,300,312,324,337,349,
%U A281590 362,374,387,400,413,426,439,452,465,479,492,506,519,533,547,561,575
%N A281590 Indices k such that A284896(k-1) and A284896(k) have a different sign.
%H A281590 Vaclav Kotesovec, <a href="/A281590/b281590.txt">Table of n, a(n) for n = 1..2612</a>
%e A281590 A284896(8) = 73, A284896(9) = -45, sign is changed, so 9 is in the sequence.
%e A281590 A284896(14) = -66, A284896(15) = 2794, sign is changed, so 15 is in the sequence.
%t A281590 nmax = 1000; A284896 = Rest[CoefficientList[Series[Product[1/(1 + x^k)^(k^2), {k, 1, nmax}], {x, 0, nmax}], x]]; csign = {1}; Do[If[(A284896[[n]] < 0 && A284896[[n+1]] >= 0) || (A284896[[n]] >= 0 && A284896[[n+1]] < 0), csign = Flatten[{csign, n + 1}]], {n, 1, Length[A284896] - 1}]; csign
%Y A281590 Cf. A284896, A281591.
%K A281590 nonn
%O A281590 1,2
%A A281590 _Vaclav Kotesovec_, Apr 14 2017