a(n) = [ C(2n,n)/2^(n+3) ].

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =3a(8) =6a(9) =11a(10) =22a(11) =43a(12) =82a(13) =158a(14) =306a(15) =591a(16) =1146a(17) =2225a(18) =4327a(19) =8426a(20) =16432a(21) =32082a(22) =62707a(23) =122687a(24) =240263a(25) =470916a(26) =923720a(27) =1813228a(28) =3561699a(29) =7000581