G.f. A(x) satisfies A(x) = (1 + x / sqrt(A(x))) / (1 - x).

Terms

a(0) =1a(1) =2a(2) =1a(3) =2a(4) =0a(5) =4a(6) =-5a(7) =16a(8) =-35a(9) =92a(10) =-231a(11) =604a(12) =-1584a(13) =4214a(14) =-11297a(15) =30538a(16) =-83096a(17) =227476a(18) =-625991a(19) =1730788a(20) =-4805594a(21) =13393690a(22) =-37458329a(23) =105089230a(24) =-295673993a(25) =834086422a(26) =-2358641375a(27) =6684761126a(28) =-18985057350a(29) =54022715452