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 A258453 #12 May 26 2018 14:54:50
%S A258453 1,-1,2,-1,0,0,2,-1,-1,0,2,0,0,-2,2,-1,0,1,2,-2,0,-2,2,0,1,0,0,0,0,-2,
%T A258453 2,-1,0,0,2,1,0,-2,0,-2,0,2,2,-2,2,-2,2,0,-1,-1,0,0,0,-2,4,0,0,0,2,-2,
%U A258453 0,-2,0,-1,0,2,2,0,0,-2,2,-1,0,0,2,-2,-2,0,2
%N A258453 G.f.: Sum_{k>0} x^((k^2 + k)/2) / (1 + x^k).
%H A258453 Seiichi Manyama, <a href="/A258453/b258453.txt">Table of n, a(n) for n = 1..5000</a>
%e A258453 G.f. = x - x^2 + 2*x^3 - x^4 + 2*x^7 - x^8 - x^9 + 2*x^11 - 2*x^14 + 2*x^15 + ...
%t A258453 a[ n_] := If[ n < 0, 0, SeriesCoefficient[ Sum[ x^((k^2 + k)/2) / (1 + x^k), {k, Sqrt[8 n + 1]}], {x, 0, n}]];
%o A258453 (PARI) {a(n) = if( n<0, 0, polcoeff( sum(k=1, sqrtint(8*n + 1), x^((k^2 + k)/2) / (1 + x^k), x * O(x^n)), n))};
%Y A258453 Cf. A001227, A048272.
%K A258453 sign
%O A258453 1,3
%A A258453 _Michael Somos_, Nov 05 2015