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 A156562 #8 Aug 03 2021 04:46:03
%S A156562 1,2,3,3,4,5,5,7,7,8,9,10,10,11,12,12,13,14,15,15,17,16,18,18,19,20,
%T A156562 21,21,22,23,23,24,25,25,27,27,28,29,30,30,31,32,32,34,34,35,36,36,37,
%U A156562 38,38,39,40,41,41,43,43,44,44,46,45,48,47,49,49,51,50,52
%N A156562 a(n) = (-1)^n*Sum_{k=1..n} A054353(k)*(-1)^k.
%H A156562 Jinyuan Wang, <a href="/A156562/b156562.txt">Table of n, a(n) for n = 1..1000</a>
%Y A156562 Cf. A054353, A156563.
%K A156562 nonn
%O A156562 1,2
%A A156562 _Benoit Cloitre_, Feb 10 2009