A047091 T(n,n), array T as in A047089.
1, 1, 4, 11, 41, 139, 515, 1871, 7004, 26191, 99137, 376300, 1437105, 5505203, 21167781, 81602665, 315395985, 1221558683, 4740410605, 18426590090, 71736136773, 279654633032, 1091552835344, 4265355947434, 16684466516559
Offset: 0