OFFSET
0,4
LINKS
Robert Israel, Table of n, a(n) for n = 0..10000
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
MAPLE
f:= proc(n) option remember;
local j;
j:= n - 2^ilog2(n);
procname(j) + 3*procname(j+1)
end proc:
f(0):= 1: f(1):= 0:
map(f, [$0..100]); # Robert Israel, Jul 10 2020
MATHEMATICA
Nest[Append[#1, #1[[#2 + 1]] + 3 #1[[#2 + 2]]] & @@ {#1, #2 - 2^Floor@ Log2@ #2} & @@ {#, Length@ #} &, {1, 0}, 82] (* Michael De Vlieger, Jul 10 2020 *)
CROSSREFS
KEYWORD
nonn,look
AUTHOR
N. J. A. Sloane, Jan 02 2010
STATUS
approved