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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 18 |
| 4 | 276 |
| 5 | 6260 |
| 6 | 190950 |
| 7 | 7523082 |
| 8 | 371286440 |
| 9 | 22356290952 |
| 10 | 1608686057610 |
| 11 | 136069954606190 |
| 12 | 13345029902628732 |
| 13 | 1500054487474871484 |
| 14 | 191349476316804534638 |
| 15 | 27464505325501082617170 |
| 16 | 4402551348139824475260240 |
| 17 | 783025812197886669354545552 |
[1,0,2,18,276,6260,190950,7523082,371286440, 22356290952,1608686057610,136069954606190, 13345029902628732,1500054487474871484, 191349476316804534638,27464505325501082617170, 4402551348139824475260240, 783025812197886669354545552] |