G.f.: A(x) = Sum_{n>=0} binomial(2*(n+1), n)/(n+1) * x^n / (1+x)^(3*(n+1)).

Terms

a(0) =1a(1) =-1a(2) =-1a(3) =1a(4) =2a(5) =0a(6) =-4a(7) =-4a(8) =5a(9) =15a(10) =4a(11) =-34a(12) =-49a(13) =35a(14) =174a(15) =106a(16) =-363a(17) =-729a(18) =173a(19) =2311a(20) =2266a(21) =-4048a(22) =-11573a(23) =-2001a(24) =32110a(25) =45110a(26) =-41692a(27) =-187550a(28) =-103297a(29) =445119