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 A220818 #13 Sep 02 2019 15:22:07
%S A220818 5,15,75,495,3600,28275,232500,1979385,17287050,154041450,1394844375,
%T A220818 12797919900,118722187125,1111672312125,10493033896875,99734572903680,
%U A220818 953755379940150,9169941599036475,88588446263805000,859511126918229075,8371534717621838250
%N A220818 Number of rooted binary MUL-trees with n leaves on the label set [5].
%H A220818 Andrew Howroyd, <a href="/A220818/b220818.txt">Table of n, a(n) for n = 1..200</a>
%H A220818 V. P. Johnson, <a href="http://people.math.sc.edu/czabarka/Theses/JohnsonThesis.pdf">Enumeration Results on Leaf Labeled Trees</a>, Ph. D. Dissertation, Univ. Southern Calif., 2012.
%t A220818 a[n_] := a[n] = If[n < 2, 5 n, If[OddQ[n], 0, (# (1 - #)/2 &)[a[n/2]]] +
%t A220818 Sum[a[i] a[n - i], {i, 1, n/2}]];
%t A220818 Array[a, 25] (* _Jean-François Alcover_, Sep 02 2019, after _Alois P. Heinz_ in A319539 *)
%Y A220818 Column 5 of A319539.
%K A220818 nonn
%O A220818 1,1
%A A220818 _N. J. A. Sloane_, Dec 22 2012
%E A220818 Terms a(11) and beyond from _Andrew Howroyd_, Sep 23 2018