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Toothpick sequence on triangular grid with word "abcb".
7

%I #15 Feb 04 2019 14:02:23

%S 0,1,3,7,13,21,27,39,49,57,69,87,111,135,155,185,203,211,223,241,265,

%T 293,321,367,405,453,499,567,633,701,751,823,859,869,881,899,923,951,

%U 979,1025,1067,1119,1179,1259,1347,1439,1529,1647,1731,1805

%N Toothpick sequence on triangular grid with word "abcb".

%C a(n) gives the number of toothpicks of length 2 in the structure after n-th stage.

%C A299477 (the first differences) gives the number of toothpicks added at n-th stage.

%C For more information about the "word" of a cellular automaton see A296612.

%H 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 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>

%H <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a>

%Y Cf. A299477 (first differences), A296612.

%Y Cf. A160120 (word "a"), A139250 (word "ab"), A296510 (word "abc"), A299478 (word "abcbc").

%K nonn,more

%O 0,3

%A _Omar E. Pol_, Feb 11 2018