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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 95 |
| 4 | 601 |
| 5 | 3951 |
| 6 | 26650 |
| 7 | 183043 |
| 8 | 1274080 |
| 9 | 8959268 |
| 10 | 63512890 |
| 11 | 453227590 |
| 12 | 3252065077 |
| 13 | 23443729683 |
| 14 | 169680654790 |
| 15 | 1232381601759 |
| 16 | 8977925594880 |
| 17 | 65579423363511 |
| 18 | 480162707557696 |
| 19 | 3523121247341469 |
| 20 | 25899477669429042 |
[1,3,16,95,601,3951,26650,183043,1274080,8959268, 63512890,453227590,3252065077,23443729683, 169680654790,1232381601759,8977925594880, 65579423363511,480162707557696,3523121247341469, 25899477669429042] |