A085568 - OEIS

%I #4 Mar 30 2012 16:49:45

%S 1,2,8,4,88,28,104,376,1904,372,30152,4952,193072,245848,64304,7984,

%T 8303392,32131172,126932136,164384184,185914544,16850280,3006076208,

%U 249890288,5554299808,21745428728,9598969456,37645191344,5687521456416,378608431568,4518712438048

%N 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.

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

%p 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;

%Y Cf. A085569-A086673.

%K nonn,frac

%O 0,2

%A _N. J. A. Sloane_, Jul 07 2003