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 A081292 #10 Jan 11 2024 03:03:02 %S A081292 0,12,50,52,56,202,204,210,212,216,226,228,232,240,810,812,818,820, %T A081292 824,842,844,850,852,856,866,868,872,880,906,908,914,916,920,930,932, %U A081292 936,944,962,964,968,976,992,3242,3244,3250,3252,3256,3274,3276,3282,3284 %N A081292 Intersection of A014486 and A079946. %C A081292 These are A014486-encodings of the binary trees (or equivalent general trees) whose left subtree (equivalently: leftmost branch) is not just a single edge. %H A081292 Antti Karttunen, <a href="/A014486/a014486.ps.gz">Initial terms illustrated in positions 0,3,6,7,8,14,15,16,17,18,...</a> %F A081292 a(n) = A014486(A081291(n)). %Y A081292 Cf. A014486, A079946. %K A081292 nonn %O A081292 1,2 %A A081292 _Antti Karttunen_, Mar 17 2003