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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 40 |
| 5 | 205 |
| 6 | 1236 |
| 7 | 8659 |
| 8 | 69280 |
| 9 | 623529 |
| 10 | 6235300 |
| 11 | 68588311 |
| 12 | 823059744 |
| 13 | 10699776685 |
| 14 | 149796873604 |
| 15 | 2246953104075 |
| 16 | 35951249665216 |
| 17 | 611171244308689 |
| 18 | 11001082397556420 |
| 19 | 209020565553571999 |
| 20 | 4180411311071440000 |
| 21 | 87788637532500240021 |
| 22 | 1931350025715005280484 |
| 23 | 44421050591445121451155 |
[0,1,2,9,40,205,1236,8659,69280,623529,6235300, 68588311,823059744,10699776685,149796873604, 2246953104075,35951249665216,611171244308689, 11001082397556420,209020565553571999, 4180411311071440000,87788637532500240021, 1931350025715005280484,44421050591445121451155] |