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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 22 |
| 4 | 91 |
| 5 | 364 |
| 6 | 1428 |
| 7 | 5537 |
| 8 | 21318 |
| 9 | 81719 |
| 10 | 312455 |
| 11 | 1193010 |
| 12 | 4552275 |
| 13 | 17368680 |
| 14 | 66284554 |
| 15 | 253086480 |
| 16 | 966955410 |
| 17 | 3697182450 |
| 18 | 14147884842 |
| 19 | 54185826156 |
| 20 | 207712333598 |
| 21 | 796937116661 |
| 22 | 3060338457400 |
| 23 | 11762344331920 |
[0,1,5,22,91,364,1428,5537,21318,81719,312455, 1193010,4552275,17368680,66284554,253086480, 966955410,3697182450,14147884842,54185826156, 207712333598,796937116661,3060338457400, 11762344331920] |