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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 518 |
| 3 | 3313 |
| 4 | 21276 |
| 5 | 136697 |
| 6 | 877196 |
| 7 | 5629192 |
| 8 | 36133600 |
| 9 | 231937284 |
| 10 | 1488661856 |
| 11 | 9554913968 |
| 12 | 61329206824 |
| 13 | 393645872364 |
| 14 | 2526623890096 |
| 15 | 16217224600128 |
| 16 | 104091133212288 |
| 17 | 668113886084144 |
| 18 | 4288315710064800 |
| 19 | 27524738318704304 |
[81,518,3313,21276,136697,877196,5629192,36133600, 231937284,1488661856,9554913968,61329206824, 393645872364,2526623890096,16217224600128, 104091133212288,668113886084144,4288315710064800, 27524738318704304] |