A210985 - OEIS

%I #18 Jan 21 2016 16:38:05

%S 1,3,7,19,63,235,919,3651,14575

%N Number of segments needed to draw the toothpick structure of A139250 as it is after 2^n stages.

%C It appears that this is also the partial sums of A039301.

%C It appears that this is also 1 together with A160128.

%H David Applegate, <a href="/A139250/a139250.anim.html">The movie version</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>

%F a(n) = A139252(2^n).

%e For n = 3, after 2^3 stages the toothpick structure of A139250 contains 43 toothpicks (A139250(2^3) = 43). However the toothpick structure can be essentially represented by 19 segments (A139252(2^3) = 19), so a(3) = 19.

%Y Cf. A007583, A039301, A139250, A139252, A147614, A160128.

%K nonn,more

%O 0,2

%A _Omar E. Pol_, Sep 11 2012