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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 23 |
| 6 | 129 |
| 7 | 894 |
| 8 | 7202 |
| 9 | 65085 |
| 10 | 651263 |
| 11 | 7161713 |
| 12 | 85922825 |
| 13 | 1116946192 |
| 14 | 15637356864 |
| 15 | 234562319757 |
| 16 | 3753007054781 |
| 17 | 63801128569995 |
| 18 | 1148420035784849 |
| 19 | 21819978138955622 |
| 20 | 436399552962252082 |
| 21 | 9164390639379582121 |
| 22 | 201616594791853840063 |
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