E.g.f. satisfies A(x)^A(x) = 1/(1 - x)^(x^2/2).

Terms

a(0) =1a(1) =0a(2) =0a(3) =3a(4) =6a(5) =20a(6) =0a(7) =-126a(8) =-1260a(9) =18360a(10) =335160a(11) =4546080a(12) =26302320a(13) =-59501520a(14) =-5703994296a(15) =-58549768200a(16) =371346066000