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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 31 |
| 6 | 181 |
| 7 | 631 |
| 8 | 1681 |
| 9 | 60481 |
| 10 | 687961 |
| 11 | 4379761 |
| 12 | 19982161 |
| 13 | 802740511 |
| 14 | 13848694861 |
| 15 | 131732390791 |
| 16 | 873339798241 |
| 17 | 38385869907841 |
| 18 | 894783905472241 |
| 19 | 11506538747852641 |
| 20 | 101612306808695521 |
| 21 | 4824806928717603871 |
| 22 | 142148609212891008421 |
[1,1,1,1,1,31,181,631,1681,60481,687961,4379761, 19982161,802740511,13848694861,131732390791, 873339798241,38385869907841,894783905472241, 11506538747852641,101612306808695521, 4824806928717603871,142148609212891008421] |