| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 34 |
| 6 | 214 |
| 7 | 1652 |
| 8 | 15121 |
| 9 | 160110 |
| 10 | 1925442 |
| 11 | 25924260 |
| 12 | 386354366 |
| 13 | 6314171932 |
| 14 | 112286067892 |
| 15 | 2158562109096 |
| 16 | 44605949528355 |
| 17 | 986049177712850 |
| 18 | 23218586050641090 |
| 19 | 580198948211652348 |
| 20 | 15334750335623526670 |
| 21 | 427408226085246086676 |
| 22 | 12528910074528593086980 |
[1,1,2,7,34,214,1652,15121,160110,1925442, 25924260,386354366,6314171932,112286067892, 2158562109096,44605949528355,986049177712850, 23218586050641090,580198948211652348, 15334750335623526670,427408226085246086676, 12528910074528593086980] |