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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 33 |
| 6 | 219 |
| 7 | 840 |
| 8 | 1055 |
| 9 | 4220 |
| 10 | 16880 |
| 11 | 95322 |
| 12 | 178500 |
| 13 | 714000 |
| 14 | 981540 |
| 15 | 1387680 |
| 16 | 7676775 |
| 17 | 7924262 |
| 18 | 12418476 |
| 19 | 12419535 |
| 20 | 16552116 |
| 21 | 19188717 |
| 22 | 44591130 |
| 23 | 66079524 |
| 24 | 77842213 |
| 25 | 178364520 |
| 26 | 294607851 |
| 27 | 363167196 |
| 28 | 610436322 |
| 29 | 823488858 |
| 30 | 950204780 |
[0,1,2,3,33,219,840,1055,4220,16880,95322,178500, 714000,981540,1387680,7676775,7924262,12418476, 12419535,16552116,19188717,44591130,66079524, 77842213,178364520,294607851,363167196,610436322, 823488858,950204780] |