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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 103 |
| 6 | 513 |
| 7 | 2761 |
| 8 | 15767 |
| 9 | 94359 |
| 10 | 586590 |
| 11 | 3763290 |
| 12 | 24792705 |
| 13 | 167078577 |
| 14 | 1148208090 |
| 15 | 8026793118 |
| 16 | 56963722223 |
| 17 | 409687815151 |
| 18 | 2981863943718 |
| 19 | 21937062144834 |
| 20 | 162958355218089 |
| 21 | 1221225517285209 |
| 22 | 9225729232653663 |
| 23 | 70209849031116183 |
| 24 | 537935616492552297 |
[1,1,2,6,23,103,513,2761,15767,94359,586590, 3763290,24792705,167078577,1148208090,8026793118, 56963722223,409687815151,2981863943718, 21937062144834,162958355218089,1221225517285209, 9225729232653663,70209849031116183, 537935616492552297] |