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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 32 |
| 6 | 179 |
| 7 | 1182 |
| 8 | 8993 |
| 9 | 77440 |
| 10 | 744425 |
| 11 | 7901410 |
| 12 | 91774375 |
| 13 | 1157782560 |
| 14 | 15764338315 |
| 15 | 230416499390 |
| 16 | 3598316747905 |
| 17 | 59792454064640 |
| 18 | 1053360827319185 |
| 19 | 19610513077334850 |
| 20 | 384703418451703175 |
| 21 | 7931544941793536800 |
| 22 | 171459202078545968675 |
| 23 | 3877969156687438765150 |
[1,0,1,2,7,32,179,1182,8993,77440,744425,7901410, 91774375,1157782560,15764338315,230416499390, 3598316747905,59792454064640,1053360827319185, 19610513077334850,384703418451703175, 7931544941793536800,171459202078545968675, 3877969156687438765150] |