G.f. satisfies: A(x) = 1 + x*A(x) / ( A(I*x)*A(-I*x) ).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =2a(6) =2a(7) =0a(8) =-5a(9) =-2a(10) =-2a(11) =8a(12) =38a(13) =20a(14) =20a(15) =-48a(16) =-269a(17) =-138a(18) =-138a(19) =392a(20) =2194a(21) =1132a(22) =1132a(23) =-3344a(24) =-19010a(25) =-9812a(26) =-9812a(27) =30032a(28) =172332a(29) =89000