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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 9 |
| 3 | 252 |
| 4 | 4464 |
| 5 | 62784 |
| 6 | 763920 |
| 7 | 8455680 |
| 8 | 88367040 |
| 9 | 896734080 |
| 10 | 8996734080 |
| 11 | 90000000000 |
| 12 | 900000000000 |
| 13 | 9000000000000 |
| 14 | 90000000000000 |
| 15 | 900000000000000 |
| 16 | 9000000000000000 |
| 17 | 90000000000000000 |
| 18 | 900000000000000000 |
| 19 | 9000000000000000000 |
| 20 | 90000000000000000000 |
| 21 | 900000000000000000000 |
[0,9,252,4464,62784,763920,8455680,88367040, 896734080,8996734080,90000000000,900000000000, 9000000000000,90000000000000,900000000000000, 9000000000000000,90000000000000000, 900000000000000000,9000000000000000000, 90000000000000000000,900000000000000000000] |