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 A080263 #7 Dec 02 2018 23:13:40 %S A080263 2,50,906,247986,4072138,1059204274,272900475786,17953590946285746, %T A080263 287705670922216138,73724537815637830834,18880972926031430339466, %U A080263 1237678872789190922262530226,316876593058175709191975346890 %N A080263 A014486-encoding of the branch-reduced binomial-mod-2 binary trees. %C A080263 These trees are obtained from the successive generations of Rule 90 cellular automaton (A070886) or Pascal's triangle computed modulo 2 (A047999), with alive cells of the automaton (respectively: the odd binomials) forming the vertices of the zigzag tree. %D A080263 J. C. P. Miller, Periodic Forests of Stunted Trees, Phil. Tran. Roy. Soc. London A266 (1970) 63; A293 (1980) 48. %H A080263 A. Karttunen, <a href="/A080263/a080263.pdf">Initial terms illustrated</a> %Y A080263 Same sequence in binary: A080264. Cf. A080265. Breadth-first-wise encodings of the same trees: A080268. Corresponding branch-reduced zigzag trees: A080293. %Y A080263 Number of edges in general trees/internal nodes in binary trees: A006046, number of zigzag-edges (those colored black in illustrations) is one less: A074330. Cf. A080978. %K A080263 nonn %O A080263 0,1 %A A080263 _Antti Karttunen_, Mar 02 2003