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 A268951 #18 Mar 20 2017 13:43:57 %S A268951 1,1,1,2,4,13,48,235,1297,8628,63902,538454,4973090,50621738, %T A268951 557399709,6636723151,84584674076,1151419603932,16640050320703, %U A268951 254656634876886,4110614617328251,69818868005928116,1244251510078579731,23216586390303085622,452567906988785409009 %N A268951 Number of growing tree trajectories (T(1),T(2),...,T(n)), where T(k) is an unlabeled tree on k nodes and T(k) can be obtained from T(k+1) by deletion of a leaf. %H A268951 Danny W. et al., <a href="http://mathoverflow.net/q/230789">Counting growing tree trajectories</a>, MathOverflow, 2016. %Y A268951 Cf. A000055, A000081, A245246. %K A268951 nonn %O A268951 1,4 %A A268951 _Max Alekseyev_, Feb 16 2016 %E A268951 Definition clarified by _Brendan McKay_, Feb 16 2016