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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 38 |
| 5 | 198 |
| 6 | 1096 |
| 7 | 6330 |
| 8 | 37722 |
| 9 | 230248 |
| 10 | 1432230 |
| 11 | 9046382 |
| 12 | 57865712 |
| 13 | 374084722 |
| 14 | 2440256850 |
| 15 | 16042605800 |
| 16 | 106181903430 |
| 17 | 706975917526 |
| 18 | 4731960602456 |
| 19 | 31820872887146 |
| 20 | 214885891901898 |
| 21 | 1456631639356008 |
| 22 | 9907950315975622 |
| 23 | 67604709705143518 |
| 24 | 462607860107453920 |
[0,1,2,8,38,198,1096,6330,37722,230248,1432230, 9046382,57865712,374084722,2440256850,16042605800, 106181903430,706975917526,4731960602456, 31820872887146,214885891901898,1456631639356008, 9907950315975622,67604709705143518, 462607860107453920] |