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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 55 |
| 4 | 214 |
| 5 | 615 |
| 6 | 1451 |
| 7 | 3829 |
| 8 | 60180 |
| 9 | 939045 |
| 10 | 8732485 |
| 11 | 56961531 |
| 12 | 289887214 |
| 13 | 1229099287 |
| 14 | 4756606869 |
| 15 | 24218431805 |
| 16 | 233925901576 |
| 17 | 2661527233449 |
| 18 | 25685325408201 |
| 19 | 203451565638511 |
| 20 | 1356903584035110 |
| 21 | 7832822232934951 |
| 22 | 40022453239462639 |
| 23 | 184228949831881593 |
[1,9,55,214,615,1451,3829,60180,939045,8732485, 56961531,289887214,1229099287,4756606869, 24218431805,233925901576,2661527233449, 25685325408201,203451565638511,1356903584035110, 7832822232934951,40022453239462639, 184228949831881593] |