T(2n+6,n), array T as in A055216.

Terms

a(0) =1a(1) =8a(2) =45a(3) =211a(4) =891a(5) =3510a(6) =13170a(7) =47672a(8) =167898a(9) =578769a(10) =1961103a(11) =6552549a(12) =21641343a(13) =70784235a(14) =229620285a(15) =739640331a(16) =2368022638a(17) =7541358405a(18) =23905443556a(19) =75468582776a(20) =237388273398a(21) =744299007994