%I #8 Feb 24 2021 02:48:18
%S 1,3,3,7,5,7,9,17,11,7
%N First differences of A161426.
%C Number of Y-toothpicks added to the sieve at the n-th round.
%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>
%H David Applegate, <a href="/A139250/a139250.anim.html">The movie version</a>
%Y Cf. A139251, A152980, A160121, A161426, A161831.
%K more,nonn
%O 1,2
%A _Omar E. Pol_ and _David Applegate_, Jun 20 2009