T(n,4), array T as in A054134.

Terms

a(0) =2a(1) =10a(2) =48a(3) =180a(4) =570a(5) =1602a(6) =4128a(7) =9972a(8) =22947a(9) =50899a(10) =109806a(11) =231988a(12) =482540a(13) =992212a(14) =2023184a(15) =4100632a(16) =8275877a(17) =16652701a(18) =33439998a(19) =67057096a(20) =134344422a(21) =268984854a(22) =538346448a(23) =1077167916a(24) =2154929607a(25) =4310595495