%I #18 May 04 2013 05:41:51

%S 0,1,11,76,435,2255,11011,51688,236028,1056210,4654430,20266312,

%T 87402185,374008635,1590144675,6724160400,28303504680,118665923310,

%U 495820606410,2065492595400,8581809094950,35572994871414,147149351758926,607555878211376

%N a(n) = f(n,n+2) where f is given in A034261.

%H Vincenzo Librandi, <a href="/A034269/b034269.txt">Table of n, a(n) for n = 0..1000</a>

%F Appears to be a(n) = 4^(n+1)*Pi^(-1/2)*GAMMA(n+3/2)/GAMMA(n+5)*(n+1)*n*(n^2+3*n+1). - _Mark van Hoeij_, Oct 30 2011.

%t Table[n*(n^2+3*n+1)*Binomial[2*n+2,n]/((n+3)*(n+4)),{n,0,20}] (* _Vaclav Kotesovec_, Oct 27 2012 *)

%o (PARI) a(n)=n*(n^2+3*n+1)*binomial(2*n+2,n)/((n+3)*(n+4)); \\ _Joerg Arndt_, May 04 2013

%K nonn,easy

%O 0,3

%A _Clark Kimberling_

%E Corrected and extended by _N. J. A. Sloane_, Apr 21 2000