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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 421 |
| 3 | 3401 |
| 4 | 3316 |
| 5 | 14639 |
| 6 | 69601 |
| 7 | 384916 |
| 8 | 1354563 |
| 9 | 4386347 |
| 10 | 20677591 |
| 11 | 97720565 |
| 12 | 380885387 |
| 13 | 1475260386 |
| 14 | 6221755468 |
| 15 | 27340927933 |
| 16 | 112702562636 |
| 17 | 453867039251 |
| 18 | 1891967304535 |
| 19 | 8027410092863 |
| 20 | 33418076358717 |
| 21 | 137512996312519 |
[0,421,3401,3316,14639,69601,384916,1354563, 4386347,20677591,97720565,380885387,1475260386, 6221755468,27340927933,112702562636,453867039251, 1891967304535,8027410092863,33418076358717, 137512996312519] |