A187221 First differences of A187220.

0, 1, 2, 4, 8, 8, 8, 16, 24, 16, 8, 16, 24, 24, 32, 56, 64, 32, 8, 16, 24, 24, 32, 56, 64, 40, 32, 56, 72, 80, 120, 176, 160, 64, 8, 16, 24, 24, 32, 56, 64, 40, 32, 56, 72, 80, 120, 176, 160, 72, 32, 56, 72, 80, 120, 176, 168, 112, 120, 184, 224, 280, 416, 512, 384, 128, 8

Offset: 0

Author

Omar E. Pol, Mar 07 2011, Mar 09 2011

Keywords

• nonn

Comments

Number of gulls (or G-toothpicks) added at n-th stage to the gullwing structure of A187220.

Apparently this is the connection between A147582 and A139251. - Omar E. Pol, Mar 11 2011

Examples

			If written as an irregular triangle begins:
0,
1,
2,
4,
8,8,
8,16,24,16,
8,16,24,24,32,56,64,32,
8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,64,
...
Also there is another version in which the layout of the irregular triangle was adjusted to reveal that the columns become constant:
.0,
.1,
.2,
.4,8,
.8,8,16,24,
16,8,16,24,24,32,56,64,
32,8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,
64,8,16,24,24,32,56,64,40,32,56,72,80,120,176,160,72,32,56,72,80...
		

Links

• David Applegate, The movie version
• David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, 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.]
• N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

Crossrefs

Cf. A139250, A139251, A147582, A187211, A187220.

Formula

a(0)=0. a(1)=1. It appears that a(n) = 2*A139251(n-1), for n >= 2.