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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 34 |
| 6 | 154 |
| 7 | 848 |
| 8 | 5552 |
| 9 | 40336 |
| 10 | 321616 |
| 11 | 2832752 |
| 12 | 27325088 |
| 13 | 285164944 |
| 14 | 3200979664 |
| 15 | 38513704448 |
| 16 | 494474723072 |
| 17 | 6744416517376 |
| 18 | 97390246272256 |
| 19 | 1484518880087552 |
| 20 | 23820397371219968 |
| 21 | 401324694629000705 |
| 22 | 7083386168647642624 |
| 23 | 130705210879629621248 |
[1,1,2,8,34,154,848,5552,40336,321616,2832752, 27325088,285164944,3200979664,38513704448, 494474723072,6744416517376,97390246272256, 1484518880087552,23820397371219968, 401324694629000705,7083386168647642624, 130705210879629621248] |