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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 31 |
| 4 | 390 |
| 5 | 7926 |
| 6 | 229448 |
| 7 | 8769552 |
| 8 | 421254088 |
| 9 | 24578690456 |
| 10 | 1699003652752 |
| 11 | 136526757080176 |
| 12 | 12565047627623648 |
| 13 | 1308650039442105504 |
| 14 | 152723805589647826368 |
| 15 | 19806995417441865105472 |
| 16 | 2834647872410303847945600 |
| 17 | 444947841160313990957842304 |
| 18 | 76198407065481146373641422336 |
| 19 | 14170329519388795065500512696832 |
[1,2,5,31,390,7926,229448,8769552,421254088, 24578690456,1699003652752,136526757080176, 12565047627623648,1308650039442105504, 152723805589647826368,19806995417441865105472, 2834647872410303847945600, 444947841160313990957842304, 76198407065481146373641422336, 14170329519388795065500512696832] |