A220514 - OEIS

%I #18 Feb 22 2023 18:27:17

%S 0,4,12,28,44,60,92,136,168,184,216,280,376,440,520,620,684,700,732,

%T 796,892,1020,1164,1332,1508,1588,1684,1860,2116,2276,2452,2664,2792,

%U 2808,2840,2904,3000,3128,3272,3448,3656,3824,4016,4272,4676,4992

%N D-toothpick sequence of the third kind starting with a X-shaped cross formed by 4 D-toothpicks.

%C This is a toothpick sequence of forking paths to 135 degrees. The sequence gives the number of toothpicks and D-toothpicks in the structure after n-th stage. A221528 (the first differences) give the number of toothpicks or D-toothpicks added at n-th stage. It appears that the structure has a fractal (or fractal-like) behavior. For more information see A194700.

%C First differs from A194434 at a(13).

%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/To#toothpick">Index entries for sequences related to toothpick sequences</a>

%F a(n) = 4*A220524(n).

%Y Cf. A139250, A194270, A194700, A194434, A220500, A220520, A220522, A221528.

%K nonn

%O 0,2

%A _Omar E. Pol_, Dec 15 2012