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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 17 |
| 4 | 72 |
| 5 | 345 |
| 6 | 1773 |
| 7 | 9525 |
| 8 | 52788 |
| 9 | 299463 |
| 10 | 1730178 |
| 11 | 10144818 |
| 12 | 60211926 |
| 13 | 361042498 |
| 14 | 2183809018 |
| 15 | 13308564682 |
| 16 | 81637319641 |
| 17 | 503667864976 |
| 18 | 3123298907641 |
| 19 | 19456221197941 |
| 20 | 121696331095636 |
| 21 | 764008782313381 |
[1,2,5,17,72,345,1773,9525,52788,299463,1730178, 10144818,60211926,361042498,2183809018, 13308564682,81637319641,503667864976, 3123298907641,19456221197941,121696331095636, 764008782313381] |