%I #10 Feb 24 2021 02:48:18

%S 1,2,2,2,4,4,2,2,4,4,4,8,12,8,2,2,4,4,4,8,12,8,4,8,12,12,16,28,32,16,

%T 2,2,4,4,4,8,12,8,4,8,12,12,16,28,32,16,4,8,12,12,16,28,32,20,16,28,

%U 36,40,60,88,80,32

%N Number of new segments added to the toothpick structure drawing at the n-th step (extensions of earlier segments are not considered).

%C First differences of A139252.

%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.]

%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>

%F a(n)=A139252(n)-A139252(n-1).

%Y Cf. A139250, A139251, A139252, A139253, A139254, A139559.

%K nonn

%O 1,2

%A _Omar E. Pol_, May 17 2008

%E Terms after a(28) from _Nathaniel Johnston_, Mar 29 2011