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 A124890 #3 Mar 30 2012 18:37:01 %S A124890 1,1,3,11,47,216,1047,5263,27191,143484,770047,4190031,23062044, %T A124890 128170182,718257014,4054089110,23026890216,131517480529,754865316100, %U A124890 4351785130675,25187530716367,146305151254984,852604651815745 %N A124890 G.f.: A(x) = (1/x)*series_reversion(x^2/G124344(x)), where G124344(x) is the g.f. of A124344 and satisfies: A(x)^2 = (1/x)*G124344(x*A(x)). %C A124890 A124344(n) is the number of ordered rooted trees on n nodes with thinning limbs. %F A124890 a(n) = A124889(n)/(n+1). a(n) = A124328(2n+1,n+1)/(n+1). %Y A124890 Cf. A124344, A124328, A124889, A124891. %K A124890 nonn %O A124890 0,3 %A A124890 _Paul D. Hanna_, Nov 12 2006