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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 104 |
| 6 | 534 |
| 7 | 3064 |
| 8 | 19558 |
| 9 | 139015 |
| 10 | 1102745 |
| 11 | 9768906 |
| 12 | 96411670 |
| 13 | 1054341718 |
| 14 | 12683130974 |
| 15 | 166505323204 |
[1,1,2,6,23,104,534,3064,19558,139015,1102745, 9768906,96411670,1054341718,12683130974, 166505323204] |