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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 15 |
| 5 | 45 |
| 6 | 540 |
| 7 | 3402 |
| 8 | 96228 |
| 9 | 1299078 |
| 10 | 85739148 |
| 11 | 2507870079 |
| 12 | 383704122087 |
| 13 | 24487299427734 |
| 14 | 8645900336407620 |
| 15 | 1209640056157393380 |
| 16 | 982320774834892454820 |
| 17 | 302358334494179897593596 |
| 18 | 563293577162657149216869348 |
[1,2,3,15,45,540,3402,96228,1299078,85739148, 2507870079,383704122087,24487299427734, 8645900336407620,1209640056157393380, 982320774834892454820,302358334494179897593596, 563293577162657149216869348] |