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 A335562 #17 Jul 22 2020 18:32:06
%S A335562 1,1,1,3,5,13,29,71,165,421,1029,2647,6593,17241,43801,115555,297513,
%T A335562 791337,2062737,5516755,14497373,38994597,103269053,278921927,
%U A335562 742950845,2014648253,5396210357,14677306503,39477832745,107701409665,290871580345,795431700707,2155140605137
%N A335562 Number of unlabelled unary-binary trees with n nodes such that every node with two children has children of different subtree sizes.
%F A335562 a(1) = 1, a(n) = a(n-1) + Sum_{k=1..n-2} (a(k)*a(n-k-1)*[k != n-k-1]).
%o A335562 (PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, va[n] = va[n-1] + sum(k=1, n-2, if (k != n-k-1, va[k]*va[n-k-1]));); va;} \\ _Michel Marcus_, Jun 14 2020
%Y A335562 Cf. A000992.
%K A335562 nonn
%O A335562 1,4
%A A335562 _Marcel K. Goh_, Jun 14 2020