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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 16 |
| 5 | 94 |
| 6 | 836 |
| 7 | 8062 |
| 8 | 92434 |
| 9 | 1187780 |
| 10 | 17103983 |
| 11 | 271660992 |
| 12 | 4722454300 |
| 13 | 89127765656 |
| 14 | 1814841101699 |
| 15 | 39650794527652 |
| 16 | 925141689393748 |
| 17 | 22957155125457704 |
| 18 | 603681013763369997 |
| 19 | 16767920412944383544 |
| 20 | 490550926763623941996 |
| 21 | 15076432260424342403648 |
| 22 | 485630804356929583800760 |
[1,0,1,2,16,94,836,8062,92434,1187780,17103983, 271660992,4722454300,89127765656,1814841101699, 39650794527652,925141689393748,22957155125457704, 603681013763369997,16767920412944383544, 490550926763623941996,15076432260424342403648, 485630804356929583800760] |