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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 17 |
| 5 | 51 |
| 6 | 161 |
| 7 | 519 |
| 8 | 1707 |
| 9 | 5711 |
| 10 | 19358 |
| 11 | 66342 |
| 12 | 229505 |
| 13 | 800333 |
| 14 | 2810370 |
| 15 | 9928806 |
| 16 | 35266403 |
| 17 | 125863071 |
| 18 | 451119566 |
| 19 | 1623142622 |
| 20 | 5860507205 |
| 21 | 21227095355 |
| 22 | 77108788287 |
| 23 | 280847802645 |
| 24 | 1025416658863 |
| 25 | 3752414144071 |
| 26 | 13760368353098 |
[1,1,2,6,17,51,161,519,1707,5711,19358,66342, 229505,800333,2810370,9928806,35266403,125863071, 451119566,1623142622,5860507205,21227095355, 77108788287,280847802645,1025416658863, 3752414144071,13760368353098] |