OFFSET
0,3
COMMENTS
It appears that this sequence is also the union of 2 and A000225. - Omar E. Pol, Mar 03 2011
LINKS
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
FORMULA
Conjectures from Colin Barker, Nov 24 2019: (Start)
G.f.: x*(1 - x - x^2 + 2*x^3) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>4.
a(n) = 2^(n-1) - 1 for n>2.
(End)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 21 2008
EXTENSIONS
More terms a(7)-a(18) from Sean A. Irvine, Feb 22 2011
More terms a(19)-a(33) from Omar E. Pol, Mar 03 2011
STATUS
approved