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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 33 |
| 4 | 202 |
| 5 | 1671 |
| 6 | 17279 |
| 7 | 234724 |
| 8 | 4081665 |
| 9 | 92343898 |
| 10 | 2711730350 |
| 11 | 103991393887 |
| 12 | 5218390436191 |
[1,2,7,33,202,1671,17279,234724,4081665,92343898, 2711730350,103991393887,5218390436191] |