A047142 T(n,n), array T as in A047140.
1, 2, 4, 10, 38, 142, 470, 1576, 5940, 22714, 83456, 305088, 1158606, 4456076, 16946498, 64189932, 246350606, 952607962, 3675557676, 14158562010, 54805236890, 213011072542, 828185178452, 3219077811678, 12537974366478
Offset: 0