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 A129162 #7 Jul 23 2017 12:22:42
%S A129162 1,5,23,103,462,2086,9493,43521,200855,932429,4350995,20395349,
%T A129162 95987113,453354623,2148027772,10206485598,48621125308,232156538970,
%U A129162 1110842790406,5325499426116,25576096186920,123030491611330
%N A129162 Sum of heights of all skew Dyck paths of semilength n.
%C A129162 A skew Dyck path is a path in the first quadrant which begins at the origin, ends on the x-axis, consists of steps U=(1,1)(up), D=(1,-1)(down) and L=(-1,-1)(left) so that up and left steps do not overlap. The length of the path is defined to be the number of its steps.
%H A129162 E. Deutsch, E. Munarini, S. Rinaldi, <a href="http://dx.doi.org/10.1016/j.jspi.2010.01.015">Skew Dyck paths</a>, J. Stat. Plann. Infer. 140 (8) (2010) 2191-2203
%F A129162 a(n) = Sum_{k=1..n} k*A129161(n,k).
%e A129162 a(2)=5 because the paths UDUD, UUDD and UUDL have heights 1, 2 and 2, respectively.
%p A129162 H[0]:=1: for k from 1 to 32 do H[k]:=simplify((1+z*H[k-1]-z)/(1-z*H[k-1])) od: for k from 1 to 32 do h[k]:=factor(simplify(H[k]-H[k-1])) od: for k from 1 to 32 do hser[k]:=series(h[k],z=0,30) od: T:=(n,k)->coeff(hser[k],z,n): seq(add(k*T(n,k),k=1..n),n=1..25);
%Y A129162 Cf. A129161.
%K A129162 nonn
%O A129162 1,2
%A A129162 _Emeric Deutsch_, Apr 03 2007