a(n) = 2*binomial(2*n+4,n)*(n+3)/(n+2).

Terms

a(0) =3a(1) =16a(2) =70a(3) =288a(4) =1155a(5) =4576a(6) =18018a(7) =70720a(8) =277134a(9) =1085280a(10) =4249388a(11) =16640960a(12) =65189475a(13) =255487680a(14) =1001800650a(15) =3930284160a(16) =15427730010a(17) =60591880800a(18) =238098549780a(19) =936100651200