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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 31 |
| 4 | 140 |
| 5 | 722 |
| 6 | 4439 |
| 7 | 32654 |
| 8 | 289519 |
| 9 | 3054067 |
| 10 | 37584620 |
| 11 | 527968286 |
| 12 | 8308434931 |
| 13 | 144345554051 |
| 14 | 2738280739075 |
| 15 | 56245013793246 |
| 16 | 1242596591479816 |
| 17 | 29366532494796900 |
| 18 | 739033832149588904 |
| 19 | 19726887762569763453 |
[1,2,8,31,140,722,4439,32654,289519,3054067, 37584620,527968286,8308434931,144345554051, 2738280739075,56245013793246,1242596591479816, 29366532494796900,739033832149588904, 19726887762569763453] |