A151885 Similar to the original toothpick sequence A139250, except that the rule is now: a toothpick changes state if its midpoint is adjacent to exactly one ON toothpick.

0, 1, 3, 5, 11, 5, 15, 17, 39, 5, 15, 25, 55, 17, 51, 61, 139, 5, 15, 25, 55, 25, 75, 85, 195, 17, 51, 85, 187, 61, 183, 217, 495, 5, 15, 25, 55, 25, 75, 85, 195, 25, 75, 125, 275, 85, 255, 305, 695, 17, 51, 85, 187, 85, 255, 289, 663

Offset: 0

Author

N. J. A. Sloane, Jul 23 2009

Keywords

• nonn

Comments

In the original toothpick sequence A139250, a toothpick simply turned ON (and stayed ON) if its midpoint was adjacent to exactly one ON toothpick.

Related to A139250 in the same way that A079315 is related to A147562.

Links

• Nathaniel Johnston, Table of n, a(n) for n = 0..925
• 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.]
• Nathaniel Johnston, C program for computing terms of A151885-A151888
• N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
• N. J. A. Sloane, Illustration of first 8 generations

Crossrefs

Cf. A151886-A151888, A139250, A139251, A147562, A079314, A079315.

Formula

a(n) = a(n-1) + A151888(n).

Extensions

Terms after a(8) from Nathaniel Johnston, Apr 02 2011