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 A083939 #9 Jan 29 2024 07:03:26 %S A083939 0,2,50,842,908,13610,13868,14642,14900,15416,218282,219308,222386, %T A083939 223412,225464,234698,235724,238802,239828,241880,247010,248036, %U A083939 250088,254192,3494570,3498668,3510962,3515060,3523256,3560138,3564236,3576530 %N A083939 A014486-encoding of binary trees whose left and right subtree are identical. %H A083939 Antti Karttunen, <a href="/A014486/a014486.ps.gz">Ten initial terms illustrated in positions 0, 1, 6, 42, 52, 385, 414, 477, 506, 555</a> %H A083939 <a href="/index/Ro#RootedTreePlanEncodings">Index entries for encodings of plane rooted trees</a> %F A083939 a(n) = A014486(A083938(n)). %K A083939 nonn %O A083939 0,2 %A A083939 _Antti Karttunen_, May 13 2003