login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A170861
a(0) = 1, a(1) = 0; a(2^i + j) = 2a(j) + 3a(j + 1) for 0 <= j < 2^i.
1
1, 0, 2, 6, 2, 6, 22, 18, 2, 6, 22, 18, 22, 78, 98, 42, 2, 6, 22, 18, 22, 78, 98, 42, 22, 78, 98, 102, 278, 450, 322, 90, 2, 6, 22, 18, 22, 78, 98, 42, 22, 78, 98, 102, 278, 450, 322, 90, 22, 78, 98, 102, 278, 450, 322, 150, 278, 450, 502, 1038, 1906, 1866, 914, 186, 2, 6, 22, 18
OFFSET
0,3
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.]
MAPLE
A[0]:= 1:A[1]:= 0:
for d from 1 to 7 do
for j from 0 to 2^d-1 do
A[2^d+j]:= 2*A[j]+3*A[j+1]
od od:
seq(A[i], i=0..2^8-1); # Robert Israel, Mar 22 2017
CROSSREFS
Sequence in context: A340857 A241040 A151705 * A229578 A078992 A062321
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 02 2010
STATUS
approved