T(n,n-4), where T is the array in A026148.

Terms

a(0) =1a(1) =4a(2) =16a(3) =56a(4) =189a(5) =616a(6) =1967a(7) =6182a(8) =19205a(9) =59124a(10) =180726a(11) =549276a(12) =1661646a(13) =5007520a(14) =15042722a(15) =45068836a(16) =134727499a(17) =401991436a(18) =1197519631a(19) =3562523314a(20) =10585937404a(21) =31424706800a(22) =93206486620a(23) =276253350360a(24) =818278951035