A151573 a(0)=1, a(1)=1; a(2^i + j) = a(j) + 2*a(j+1) for 0 <= j < 2^i.

1, 1, 3, 7, 3, 7, 17, 13, 3, 7, 17, 13, 17, 41, 43, 19, 3, 7, 17, 13, 17, 41, 43, 19, 17, 41, 43, 47, 99, 127, 81, 25, 3, 7, 17, 13, 17, 41, 43, 19, 17, 41, 43, 47, 99, 127, 81, 25, 17, 41, 43, 47, 99, 127, 81, 53, 99, 127, 137, 245, 353, 289, 131, 31, 3, 7, 17, 13, 17, 41, 43, 19, 17

Offset: 0

Author

N. J. A. Sloane, May 25 2009

Keywords

• nonn

Comments

Equals A151572 + A151703.

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

Crossrefs

For the recurrence a(2^i+j) = C*a(j) + D*a(j+1), a(0) = A, a(1) = B for following values of (A B C D) see: (0 1 1 1) A118977, (1 0 1 1) A151702, (1 1 1 1) A151570, (1 2 1 1) A151571, (0 1 1 2) A151572, (1 0 1 2) A151703, (1 1 1 2) A151573, (1 2 1 2) A151574, (0 1 2 1) A160552, (1 0 2 1) A151704, (1 1 2 1) A151568, (1 2 2 1) A151569, (0 1 2 2) A151705, (1 0 2 2) A151706, (1 1 2 2) A151707, (1 2 2 2) A151708.

Programs

Maple

N:= 10: # to get a(0) to a(2^(N+1)-1)
a[0]:= 1:
a[1]:= 1:
for i from 1 to N do
  for j from 0 to 2^i-1 do
    a[2^i+j]:= a[j]+2*a[j+1]
  od
od:
seq(a[i],i=0..2^(N+1)-1); # Robert Israel, May 28 2014

Mathematica

a = {1, 1}; Do[AppendTo[a, a[[j]] + 2 a[[j + 1]]], {i, 6}, {j, 2^i}]; a (* Ivan Neretin, Jun 28 2017 *)