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 A048809 #15 Dec 19 2015 13:11:26 %S A048809 1,1,2,3,6,8,15,23,39,61,102,161,265,420,682,1087,1753,2790,4476,7120, %T A048809 11376,18075,28785,45666,72530,114882,182040,287878,455231,718755, %U A048809 1134491,1788461,2818140,4436000,6978932,10969695,17232572,27049320 %N A048809 Number of rooted trees with n nodes with every leaf at height 4. %H A048809 Alois P. Heinz, <a href="/A048809/b048809.txt">Table of n, a(n) for n = 5..1000</a> %H A048809 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %H A048809 <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a> %F A048809 Euler transform of A048808 shifted right. %Y A048809 Cf. A048808-A048816. %Y A048809 Column k=4 of A244925. %K A048809 nonn %O A048809 5,3 %A A048809 _Christian G. Bower_, Apr 15 1999