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 A299476 #15 Feb 04 2019 14:02:23 %S A299476 0,1,3,7,13,21,27,39,49,57,69,87,111,135,155,185,203,211,223,241,265, %T A299476 293,321,367,405,453,499,567,633,701,751,823,859,869,881,899,923,951, %U A299476 979,1025,1067,1119,1179,1259,1347,1439,1529,1647,1731,1805 %N A299476 Toothpick sequence on triangular grid with word "abcb". %C A299476 a(n) gives the number of toothpicks of length 2 in the structure after n-th stage. %C A299476 A299477 (the first differences) gives the number of toothpicks added at n-th stage. %C A299476 For more information about the "word" of a cellular automaton see A296612. %H A299476 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %H A299476 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a> %H A299476 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %Y A299476 Cf. A299477 (first differences), A296612. %Y A299476 Cf. A160120 (word "a"), A139250 (word "ab"), A296510 (word "abc"), A299478 (word "abcbc"). %K A299476 nonn,more %O A299476 0,3 %A A299476 _Omar E. Pol_, Feb 11 2018