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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 90 |
| 6 | 726 |
| 7 | 7089 |
| 8 | 78369 |
| 9 | 973404 |
| 10 | 13377156 |
| 11 | 201443165 |
| 12 | 3297443264 |
| 13 | 58304208767 |
| 14 | 1107693755122 |
[0,1,3,13,90,726,7089,78369,973404,13377156, 201443165,3297443264,58304208767,1107693755122] |