A151681 a(n) = sum_{k >= 0, k even} binomial(wt(n+k),k+1), where wt() = A000120().

1, 2, 1, 2, 2, 4, 1, 2, 2, 4, 2, 5, 4, 7, 1, 2, 2, 4, 2, 5, 4, 7, 2, 5, 4, 8, 5, 12, 7, 11, 1, 2, 2, 4, 2, 5, 4, 7, 2, 5, 4, 8, 5, 12, 7, 11, 2, 5, 4, 8, 5, 12, 7, 12, 5, 12, 8, 17, 12, 26, 11, 16, 1, 2, 2, 4, 2, 5, 4, 7, 2, 5, 4, 8, 5, 12, 7, 11, 2, 5, 4, 8, 5, 12, 7, 12, 5, 12, 8, 17, 12, 26, 11, 16

Offset

0,2

Links

Table of n, a(n) for n=0..93.

Maple

wt := proc(n) local w, m, i; w := 0; m := n; while m > 0 do i := m mod 2; w := w+i; m := (m-i)/2; od; w; end:
f:=proc(n) local t1, k; global wt; t1:=0; for k from 0 to 20 do if k mod 2 = 0 then t1:=t1+binomial(wt(n+k), k); fi; od; t1; end;

Crossrefs

Sequence in context: A130831 A151678 A273126 * A336138 A366600 A365461

Adjacent sequences: A151678 A151679 A151680 * A151682 A151683 A151684

Keyword

nonn

Author

N. J. A. Sloane, Jun 01 2009

Status

approved