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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 39 |
| 3 | 258 |
| 4 | 1719 |
| 5 | 11496 |
| 6 | 77052 |
| 7 | 517194 |
| 8 | 3475071 |
| 9 | 23366598 |
| 10 | 157206519 |
| 11 | 1058119992 |
| 12 | 7124428836 |
| 13 | 47983020624 |
| 14 | 323240752272 |
| 15 | 2177956129818 |
| 16 | 14677216121871 |
| 17 | 98923498131762 |
| 18 | 666819212874501 |
| 19 | 4495342330033938 |
| 20 | 30308036621747679 |
| 21 | 204356509814519712 |
[1,6,39,258,1719,11496,77052,517194,3475071, 23366598,157206519,1058119992,7124428836, 47983020624,323240752272,2177956129818, 14677216121871,98923498131762,666819212874501, 4495342330033938,30308036621747679, 204356509814519712] |