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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 10 |
| 5 | 31 |
| 6 | 271 |
| 7 | 1534 |
| 8 | 14603 |
| 9 | 120173 |
| 10 | 1310224 |
| 11 | 13947517 |
| 12 | 175477699 |
| 13 | 2265702388 |
| 14 | 32673218085 |
| 15 | 492565328493 |
| 16 | 8053045395018 |
| 17 | 138334722101571 |
| 18 | 2535114408394699 |
| 19 | 48790865853110950 |
| 20 | 991843960201311455 |
| 21 | 21121971129683138297 |
| 22 | 471959969940724275432 |
[1,0,1,1,10,31,271,1534,14603,120173,1310224, 13947517,175477699,2265702388,32673218085, 492565328493,8053045395018,138334722101571, 2535114408394699,48790865853110950, 991843960201311455,21121971129683138297, 471959969940724275432] |