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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 132 |
| 7 | 428 |
| 8 | 1420 |
| 9 | 4796 |
| 10 | 16432 |
| 11 | 56966 |
| 12 | 199444 |
| 13 | 704146 |
| 14 | 2504000 |
| 15 | 8960445 |
| 16 | 32241670 |
| 17 | 116580200 |
| 18 | 423372684 |
| 19 | 1543542369 |
| 20 | 5647383786 |
| 21 | 20728481590 |
| 22 | 76305607480 |
| 23 | 281648344965 |
| 24 | 1042139463066 |
| 25 | 3864822037106 |
| 26 | 14362983740692 |
| 27 | 53481776523398 |
[1,1,2,5,14,42,132,428,1420,4796,16432,56966, 199444,704146,2504000,8960445,32241670,116580200, 423372684,1543542369,5647383786,20728481590, 76305607480,281648344965,1042139463066, 3864822037106,14362983740692,53481776523398] |