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

%I #14 Feb 04 2019 14:02:48

%S 0,1,3,7,13,21,27,33,43,59,79,91,101,117,137,169,193,215,249,285,325,

%T 341,355,375,399,439,471,503,547,595,659,707,749,807,877,981,1055,

%U 1115,1193,1271,1351,1375,1389,1409,1433,1473,1509,1549,1599,1651,1723

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

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

%C A299479 (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. A299479 (first differences).

%Y Cf. A160120 (word "a"), A139250 (word "ab"), A296510 (word "abc"), A299476 (word "abcb").

%K nonn,more

%O 0,3

%A _Omar E. Pol_, Feb 11 2018