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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 35 |
| 4 | 226 |
| 5 | 1561 |
| 6 | 11276 |
| 7 | 84150 |
| 8 | 643730 |
| 9 | 5021038 |
| 10 | 39781858 |
| 11 | 319282210 |
| 12 | 2590312872 |
| 13 | 21208628405 |
| 14 | 175024439504 |
| 15 | 1454329099044 |
| 16 | 12157356271998 |
| 17 | 102170610282040 |
| 18 | 862721635191860 |
| 19 | 7315768816166027 |
| 20 | 62274763166575410 |
| 21 | 531950072655682896 |
| 22 | 4558282056420235664 |
[1,1,6,35,226,1561,11276,84150,643730,5021038, 39781858,319282210,2590312872,21208628405, 175024439504,1454329099044,12157356271998, 102170610282040,862721635191860,7315768816166027, 62274763166575410,531950072655682896, 4558282056420235664] |