A085568 Numerator of 2*Sum(C(n,w)/(2*w+1),w=0..n/2-1)+C(n,n/2)/(n+1) if n is even, or of 2*Sum(C(n,w)/(2*w+1),w=0..(n-1)/2) if n is odd.

1, 2, 8, 4, 88, 28, 104, 376, 1904, 372, 30152, 4952, 193072, 245848, 64304, 7984, 8303392, 32131172, 126932136, 164384184, 185914544, 16850280, 3006076208, 249890288, 5554299808, 21745428728, 9598969456, 37645191344, 5687521456416, 378608431568, 4518712438048

Offset

0,2

Links

Table of n, a(n) for n=0..30.

Example

1, 2, 8/3, 4, 88/15, 28/3, 104/7, 376/15, 1904/45, 372/5, 30152/231, ...

Maple

b := binomial; f1 := n->if n mod 2 = 0 then 2*add(b(n, w)/(2*w+1), w=0..n/2-1)+b(n, n/2)/(n+1); else 2*add(b(n, w)/(2*w+1), w=0..(n-1)/2); fi;

Crossrefs

Cf. A085569-A086673.

Sequence in context: A195923 A213456 A210422 * A054671 A203269 A011058

Adjacent sequences: A085565 A085566 A085567 * A085569 A085570 A085571

Keyword

nonn,frac

Author

N. J. A. Sloane, Jul 07 2003

Status

approved