T(2n+4,n), array T as in A055794.

Terms

a(0) =1a(1) =6a(2) =22a(3) =64a(4) =162a(5) =372a(6) =792a(7) =1584a(8) =3003a(9) =5434a(10) =9438a(11) =15808a(12) =25636a(13) =40392a(14) =62016a(15) =93024a(16) =136629a(17) =196878a(18) =278806a(19) =388608a(20) =533830a(21) =723580a(22) =968760a(23) =1282320a(24) =1679535a(25) =2178306a(26) =2799486a(27) =3567232a(28) =4509384