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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 66 |
| 4 | 680 |
| 5 | 9054 |
| 6 | 147811 |
| 7 | 2855574 |
| 8 | 63656423 |
| 9 | 1607072112 |
| 10 | 45294892304 |
| 11 | 1409197189256 |
| 12 | 47954491442089 |
| 13 | 1771493331491354 |
| 14 | 70590010219153189 |
| 15 | 3017771375030039066 |
| 16 | 137763757493141082536 |
| 17 | 6688261925293875095950 |
[1,2,9,66,680,9054,147811,2855574,63656423, 1607072112,45294892304,1409197189256, 47954491442089,1771493331491354,70590010219153189, 3017771375030039066,137763757493141082536, 6688261925293875095950] |