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 A101488 #13 Jul 25 2018 06:14:34 %S A101488 1,1,1,2,4,10,26,73,213,645,2007,6391,20741,68407,228753,774162, %T A101488 2647548,9138342,31802118,111489492,393442848,1396771812,4985732628, %U A101488 17884908282,64449398994,233220788850,847211744806,3088649627798 %N A101488 Number of naturally embedded binary trees with n nodes that have no label greater than 0. %H A101488 M. Bousquet-Mélou, <a href="https://arxiv.org/abs/math/0501266">Limit laws for embedded trees</a>, arXiv:math/0501266 [math.CO], 2005. %F A101488 G.f.: ((1-4z)^(3/2)-1+8z-2z^2)/(2z(1+z)). %t A101488 CoefficientList[((1-4z)^(3/2)-1+8z-2z^2)/(2z(1+z)) + O[z]^28, z] (* _Jean-François Alcover_, Jul 25 2018 *) %Y A101488 First row of array A101489. %K A101488 nonn %O A101488 0,4 %A A101488 _Ralf Stephan_, Jan 21 2005