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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 60 |
| 6 | 225 |
| 7 | 1148 |
| 8 | 4235 |
| 9 | 22296 |
| 10 | 82425 |
| 11 | 440308 |
| 12 | 1634435 |
| 13 | 8809736 |
| 14 | 32819839 |
| 15 | 178029138 |
| 16 | 665162897 |
| 17 | 3625521728 |
| 18 | 13577768505 |
[1,3,13,60,225,1148,4235,22296,82425,440308, 1634435,8809736,32819839,178029138,665162897, 3625521728,13577768505] |