A151687 G.f.: x + x^2 * Product_{n>=0} (1 + x^(2^n-1) + x^(2^n)).

0, 1, 2, 3, 3, 3, 5, 6, 4, 3, 5, 6, 6, 8, 11, 10, 5, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 6, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 8, 8, 11, 12, 14, 19, 21, 17, 15, 19, 23, 26, 33, 40, 36, 21, 7, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 8, 8

Offset: 0

Author

N. J. A. Sloane, Jun 03 2009

Keywords

• nonn

Comments

Apart from initial terms and offset, same as A160573, but has a slightly nice recurrence.

Crossrefs

Rows of triangle in A118977 converge to this.

Programs

Maple

G:= x + x^2 * mul( 1 + x^(2^n-1) + x^(2^n), n=0..20);

Formula

a(0) = 0, a(2^k) = k+1; for n >= 3, if n = 2^i + j, 1 <= j < 2^i, a(n) = a(j) + a(j+1).