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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 19 |
| 4 | 126 |
| 5 | 782 |
| 6 | 4720 |
| 7 | 28158 |
| 8 | 167076 |
| 9 | 988976 |
| 10 | 5848884 |
| 11 | 34587791 |
| 12 | 204607678 |
| 13 | 1211072430 |
| 14 | 7173288330 |
| 15 | 42519596826 |
| 16 | 252225457356 |
| 17 | 1497318796416 |
| 18 | 8895212879140 |
| 19 | 52881434260371 |
| 20 | 314587526985030 |
| 21 | 1872652395544866 |
| 22 | 11154143632096962 |
| 23 | 66476020466258370 |
[0,3,19,126,782,4720,28158,167076,988976,5848884, 34587791,204607678,1211072430,7173288330, 42519596826,252225457356,1497318796416, 8895212879140,52881434260371,314587526985030, 1872652395544866,11154143632096962, 66476020466258370] |