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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 9 |
| 4 | 66 |
| 5 | 345 |
| 6 | 1590 |
| 7 | 6909 |
| 8 | 29106 |
| 9 | 120465 |
| 10 | 493230 |
| 11 | 2005509 |
| 12 | 8116746 |
| 13 | 32744985 |
| 14 | 131801670 |
| 15 | 529647309 |
| 16 | 2125861986 |
| 17 | 8525167905 |
| 18 | 34165634910 |
| 19 | 136857036309 |
| 20 | 548010848826 |
| 21 | 2193789933225 |
| 22 | 8780396200950 |
| 23 | 35137287916509 |
[0,0,9,66,345,1590,6909,29106,120465,493230, 2005509,8116746,32744985,131801670,529647309, 2125861986,8525167905,34165634910,136857036309, 548010848826,2193789933225,8780396200950, 35137287916509] |