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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 64 |
| 6 | 314 |
| 7 | 1633 |
| 8 | 8826 |
| 9 | 49107 |
| 10 | 279349 |
| 11 | 1617290 |
| 12 | 9498099 |
| 13 | 56445918 |
| 14 | 338817460 |
| 15 | 2051182532 |
| 16 | 12509647159 |
| 17 | 76785827812 |
| 18 | 474000090118 |
| 19 | 2940761033970 |
| 20 | 18327028477625 |
| 21 | 114677403429121 |
| 22 | 720191795608082 |
| 23 | 4537925593859911 |
| 24 | 28679991910774479 |
| 25 | 181761824439041725 |
[1,1,1,4,14,64,314,1633,8826,49107,279349,1617290, 9498099,56445918,338817460,2051182532,12509647159, 76785827812,474000090118,2940761033970, 18327028477625,114677403429121,720191795608082, 4537925593859911,28679991910774479, 181761824439041725] |