OFFSET
0,3
COMMENTS
Essentially the first differences of A183126.
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
a(n) = 4*(1 + 3^A000120(n-2)), n >= 3. - Nathaniel Johnston, Apr 06 2011
MATHEMATICA
a[n_] := 4*(1 + 3^DigitCount[n-2, 2, 1]); a[0] = 0; a[1] = 1; a[2] = 6; Array[a, 100, 0] (* Amiram Eldar, Aug 01 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Mar 28 2011
EXTENSIONS
a(0)-a(10) confirmed and a(11)-a(35) added by John W. Layman, Mar 30 2011
a(36)-a(47) from Nathaniel Johnston, Apr 06 2011
More terms from Amiram Eldar, Aug 01 2023
STATUS
approved