1, 1, 2, 6, 20, 68, 232, 792, ...
1, 2, 4, 10, 30, 98, 330, 1122, ...
2, 4, 8, 18, 48, 146, 476, 1598, ...
6, 10, 18, 36, 84, 230, 706, 2304, ...
20, 30, 48, 84, 168, 398, 1104, 3408, ...
68, 98, 146, 230, 398, 796, 1900, 5308, ...
232, 330, 476, 706, 1104, 1900, 3800, 9108, ...
792, 1122, 1598, 2304, 3408, 5308, 9108, 18216, ...
2704, 3826, 5424, 7728, 11136, 16444, 25552, 43768, ...
9232, 13058, 18482, 26210, 37346, 53790, 79342, 123110, ...