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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 12 |
| 3 | 81 |
| 4 | 598 |
| 5 | 4708 |
| 6 | 38622 |
| 7 | 327823 |
| 8 | 2847315 |
| 9 | 25163920 |
| 10 | 225457188 |
| 11 | 2042143752 |
| 12 | 18663517814 |
| 13 | 171846353051 |
| 14 | 1592315669558 |
| 15 | 14834375047080 |
| 16 | 138850713196545 |
| 17 | 1305003833233144 |
| 18 | 12309801809090282 |
| 19 | 116490773908518079 |
| 20 | 1105570064097792198 |
| 21 | 10519869248735544757 |
| 22 | 100335959685809643520 |
[2,12,81,598,4708,38622,327823,2847315,25163920, 225457188,2042143752,18663517814,171846353051, 1592315669558,14834375047080,138850713196545, 1305003833233144,12309801809090282, 116490773908518079,1105570064097792198, 10519869248735544757,100335959685809643520] |