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 A152536 #20 Aug 09 2021 16:23:58
%S A152536 1,1,1,2,3,6,10,23,47,110,246,617,1602,4035,11481,29927,95503,249926,
%T A152536 871030,2316317,8879558,23674841,98329551,264329177,1191578522,
%U A152536 3207278255,15543026747,42011308653,218668538441,591460307157,3285749117475,8905905152798,52700813279423
%N A152536 a(n) = Sum_{k=0..binomial(n,2)} (-1)^k*A152534(n,k).
%H A152536 Alois P. Heinz, <a href="/A152536/b152536.txt">Table of n, a(n) for n = 0..100</a>
%p A152536 A152536 := proc(n)
%p A152536 add( (-1)^k*A152534(n,k),k=0..binomial(n,2)) ;
%p A152536 end proc: # _R. J. Mathar_, Jun 15 2013
%Y A152536 Cf. A152534.
%K A152536 nonn
%O A152536 0,4
%A A152536 _Vladeta Jovovic_, Dec 06 2008
%E A152536 a(17)-a(20) from _Vaclav Kotesovec_, May 24 2020
%E A152536 a(0), a(21)-a(32) from _Alois P. Heinz_, Aug 09 2021