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 A355910 #7 Sep 19 2022 14:57:29
%S A355910 1,1,1,2,3,4,6,9,14,21,31,47,71,106,159,239,358,537,806,1209,1813,
%T A355910 2719,4079,6119
%N A355910 Number of nodes at level n in the tree T_{-2}.
%C A355910 First differences of A355909.
%H A355910 Don Knuth, <a href="http://cs.stanford.edu/~knuth/papers/ambidextrous.pdf">Ambidextrous Numbers</a>, Preprint, September 2022. See (12.6).
%Y A355910 Cf. A355904-A355909, A355911-A355913.
%K A355910 nonn,more
%O A355910 0,4
%A A355910 _N. J. A. Sloane_, Sep 19 2022