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 A081629 #15 Jul 26 2025 17:19:44 %S A081629 1,1,9,117,1989,41709,1038975,29947185,979687005,35839643175, %T A081629 1449091813035,64144495494825,3084209792570721,160023238477245789, %U A081629 8909102551102555002,529651263967161225648,33482356679629151295651 %N A081629 Number of 9-level labeled rooted trees with n leaves. %D A081629 J. Ginsburg, Iterated exponentials, Scripta Math., 11 (1945), 340-353. %D A081629 T. Hogg and B. A. Huberman, Attractors on finite sets: the dissipative dynamics of computing structures, Phys. Review A 32 (1985), 2338-2346. %H A081629 Alois P. Heinz, <a href="/A081629/b081629.txt">Table of n, a(n) for n = 0..150</a> %F A081629 E.g.f.: exp(exp(exp(exp(exp(exp(exp(exp(exp(x)-1)-1)-1)-1)-1)-1)-1)-1). %o A081629 (PARI) a(n)=local(X); if(n<0,0,X=x+x*O(x^n); n!*polcoeff(exp(exp(exp(exp(exp(exp(exp(exp(exp(X)-1)-1)-1)-1)-1)-1)-1)-1),n)) %Y A081629 Cf. A000110, A000258, A000307, A000357, A001669. %Y A081629 Column k=8 of A144150. %K A081629 nonn %O A081629 0,3 %A A081629 _Benoit Cloitre_, Apr 23 2003