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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 18 |
| 4 | 124 |
| 5 | 935 |
| 6 | 7443 |
| 7 | 61510 |
| 8 | 522467 |
| 9 | 4532452 |
| 10 | 39985628 |
| 11 | 357641094 |
| 12 | 3235846003 |
| 13 | 29565353095 |
| 14 | 272429349163 |
| 15 | 2528938553028 |
| 16 | 23629834081955 |
| 17 | 222080711420655 |
| 18 | 2098112946860819 |
| 19 | 19915641133236764 |
| 20 | 189853287434733709 |
| 21 | 1816924035668823659 |
| 22 | 17450483777418686431 |
[1,1,3,18,124,935,7443,61510,522467,4532452, 39985628,357641094,3235846003,29565353095, 272429349163,2528938553028,23629834081955, 222080711420655,2098112946860819, 19915641133236764,189853287434733709, 1816924035668823659,17450483777418686431] |