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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 40 |
| 3 | 328 |
| 4 | 2536 |
| 5 | 19912 |
| 6 | 158056 |
| 7 | 1260616 |
| 8 | 10073320 |
| 9 | 80551624 |
| 10 | 644308072 |
| 11 | 5154149704 |
| 12 | 41232252904 |
| 13 | 329855188936 |
| 14 | 2638833008488 |
| 15 | 21110638558792 |
| 16 | 168885031942888 |
| 17 | 1351080025960648 |
| 18 | 10808639518937704 |
| 19 | 86469114085259080 |
| 20 | 691752906483344872 |
| 21 | 5534023233270575560 |
| 22 | 44272185810376054120 |
[0,40,328,2536,19912,158056,1260616,10073320, 80551624,644308072,5154149704,41232252904, 329855188936,2638833008488,21110638558792, 168885031942888,1351080025960648, 10808639518937704,86469114085259080, 691752906483344872,5534023233270575560, 44272185810376054120] |