A085570 If n mod 2 = 0 then 2*Sum(floor(C(n,w)/(2*w+1)),w=0..n/2-1)+floor(C(n,n/2)/(n+1)) otherwise 2*Sum(floor(C(n,w)/(2*w+1)),w=0..(n-1)/2).

1, 2, 2, 4, 5, 8, 14, 24, 39, 74, 128, 232, 423, 776, 1426, 2660, 4931, 9268, 17346, 32840, 61903, 117832, 223410, 427156, 813812, 1561830, 2987535, 5751742, 11039759, 21312036, 41025866, 79386066, 153208323, 297072312, 574604611, 1116186954, 2163216427

Offset: 0

Author

N. J. A. Sloane, Jul 07 2003

Keywords

• nonn

Crossrefs

Cf. A085568-A086673.

Programs

Maple

b := binomial; f2 := n->if n mod 2 = 0 then 2*add(floor(b(n,w)/(2*w+1)),w=0..n/2-1)+floor(b(n,n/2)/(n+1)); else 2*add(floor(b(n,w)/(2*w+1)),w=0..(n-1)/2); fi;