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 A227806 #8 Jun 07 2021 12:00:06 %S A227806 1,1,3,5,11,22,49,104,232,513,1159,2619,5989,13734,31729,73555,171377, %T A227806 400631,940104,2212542,5222932,12360976,29327260,69735757,166170966, %U A227806 396727768,948897250,2273409345,5455374972,13110384631,31550978034,76029236983,183437066950 %N A227806 Number of rooted identity trees with n nodes and exactly 2 subtrees from the root. %H A227806 Alois P. Heinz, <a href="/A227806/b227806.txt">Table of n, a(n) for n = 4..800</a> %F A227806 a(n) ~ c * d^n / n^(3/2), where d = A246169 = 2.51754035263200389079535459846344... and c = 0.14400421547102520752812171064737721... - _Vaclav Kotesovec_, Jun 07 2021 %e A227806 : o : o : o o o : %e A227806 : / \ : / \ : / \ / \ / \ : %e A227806 : o o : o o : o o o o o o : %e A227806 : | : | : | | / \ | : %e A227806 : o : o : o o o o o : %e A227806 : : | : | | | : %e A227806 : : o : o o o : %e A227806 : : : | : %e A227806 : n=4 : n=5 : n=6 o : %Y A227806 Column k=2 of A227774. %K A227806 nonn %O A227806 4,3 %A A227806 _Alois P. Heinz_, Jul 31 2013