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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 36 |
| 5 | 221 |
| 6 | 1431 |
| 7 | 10121 |
| 8 | 80311 |
| 9 | 718106 |
| 10 | 7111976 |
| 11 | 76201501 |
| 12 | 868288401 |
| 13 | 10438492181 |
| 14 | 132166853861 |
| 15 | 1763179150946 |
| 16 | 24776241643056 |
| 17 | 365971430085021 |
| 18 | 5662954240306111 |
| 19 | 91450179009971181 |
| 20 | 1536249848608545451 |
| 21 | 26782376261726525126 |
| 22 | 483792982362049317676 |
[1,1,1,6,36,221,1431,10121,80311,718106,7111976, 76201501,868288401,10438492181,132166853861, 1763179150946,24776241643056,365971430085021, 5662954240306111,91450179009971181, 1536249848608545451,26782376261726525126, 483792982362049317676] |