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%I #13 Jan 19 2015 23:27:51
%S 0,6,18,18,54,18,54,54,126,54,54,54,126,90,126,162,306,162,54,54,126,
%T 90,126,162,306,198,126,162,306,306,342,414,702,486,126,54,126,90,126,
%U 162,306,198,126,162,306,306,342,414,702,522,198,162
%N First differences of A253770.
%C Number of cells turned "ON" at n-th stage of cellular automaton of A253770.
%C Also 6 times the number of Y-toothpicks added at n-th stage in the Y-toothpick structure of A160120.
%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>
%F a(n) = 6*A160121(n).
%e Positive terms can be written as a triangle in which row lengths is A011782 as shown below:
%e 6;
%e 18;
%e 18, 54;
%e 18, 54,54,126;
%e 54, 54,54,126,90,126,162,306;
%e 162, 54,54,126,90,126,162,306,198,126,162,306,306,342,414,702;
%e 486,126,54,126,90,126,162,306,198,126,162,306,306,342,414,702,522,198,162,...
%Y Cf. A139251, A147582, A151724, A160121, A161645, A182633, A250301, A253770.
%K nonn,tabf
%O 0,2
%A _Omar E. Pol_, Jan 13 2015