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 A291886 #6 Sep 05 2017 12:14:23
%S A291886 0,1,3,8,24,73,239,808,2839,10173,37107,136778,508622,1902931,7156180,
%T A291886 27020991,102387426,389129477,1482851762,5664065704,21681357734,
%U A291886 83154466615,319486977769,1229491584784,4738571829454,18288152053984,70672285064968,273430196389027
%N A291886 Total height of all symmetrically unique Dyck paths of semilength n.
%H A291886 Alois P. Heinz, <a href="/A291886/b291886.txt">Table of n, a(n) for n = 0..600</a>
%F A291886 a(n) = Sum_{k=1..n} k * A291883(n,k)
%Y A291886 Cf. A291883.
%K A291886 nonn
%O A291886 0,3
%A A291886 _Alois P. Heinz_, Sep 05 2017