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%I #19 Feb 24 2021 02:48:18
%S 0,4,8,16,24,32,40,56,72,80,88,104,120,136,160,200,232,240,248,264,
%T 280,296,320,360,392,408,432,472,512,560,640,744,808,816,824,840,856,
%U 872,896,936,968,984,1008,1048,1088,1136,1216,1320,1384,1400,1424,1464,1504,1552
%N Toothpick sequence starting from a cross formed by 4 toothpicks.
%C On the infinite square grid we start at stage 0 with no toothpicks. Toothpicks have length 2. At stage 1 we place two consecutive toothpicks in the vertical direction and two consecutive toothpicks in the horizontal direction forming a cross centered at the origin. At stage 2 we place four toothpicks. At stage 3 we place eight toothpicks. For more information about the toothpick sequences see A139250. - Omar E. Pol, Nov 24 2011
%H David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.], which is also available at <a href="http://arxiv.org/abs/1004.3036">arXiv:1004.3036v2</a>
%H Mathematical Association of America, <a href="http://maanumberaday.blogspot.com/2011/10/1136.html">NumberADay: 1136</a>
%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*A160406(n).
%Y Cf. A139250, A139251, A160736, A160738, A160741.
%Y Cf. A160170, A160426, A194432, A194434.
%K nonn
%O 0,2
%A _Omar E. Pol_, May 25 2009
%E More terms from _N. J. A. Sloane_, May 25 2009
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