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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 14 |
| 3 | 56 |
| 4 | 446 |
| 5 | 2152 |
| 6 | 18248 |
| 7 | 97120 |
| 8 | 848254 |
| 9 | 4796552 |
| 10 | 42454664 |
| 11 | 250140640 |
| 12 | 2226532712 |
| 13 | 13516860320 |
| 14 | 120553738144 |
| 15 | 748819997056 |
| 16 | 6679690686334 |
| 17 | 42254745008840 |
| 18 | 376638926040392 |
| 19 | 2418457241945056 |
| 20 | 21530200591563496 |
| 21 | 139992790135717792 |
| 22 | 1244418656720926624 |
| 23 | 8178446389043428736 |
[1,2,14,56,446,2152,18248,97120,848254,4796552, 42454664,250140640,2226532712,13516860320, 120553738144,748819997056,6679690686334, 42254745008840,376638926040392,2418457241945056, 21530200591563496,139992790135717792, 1244418656720926624,8178446389043428736] |