G.f.: 1/((1-x^2)^3*(1-x)^4).

Terms

a(0) =1a(1) =4a(2) =13a(3) =32a(4) =71a(5) =140a(6) =259a(7) =448a(8) =742a(9) =1176a(10) =1806a(11) =2688a(12) =3906a(13) =5544a(14) =7722a(15) =10560a(16) =14223a(17) =18876a(18) =24739a(19) =32032a(20) =41041a(21) =52052a(22) =65429a(23) =81536a(24) =100828a(25) =123760a(26) =150892a(27) =182784a(28) =220116a(29) =263568