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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 32 |
| 4 | 186 |
| 5 | 1222 |
| 6 | 9086 |
| 7 | 75882 |
| 8 | 705298 |
| 9 | 7231862 |
| 10 | 81160422 |
| 11 | 990024466 |
| 12 | 13047411482 |
| 13 | 184788881838 |
| 14 | 2799459801742 |
| 15 | 45178128866282 |
| 16 | 773829771302946 |
| 17 | 14021761172671462 |
| 18 | 267991492197471158 |
| 19 | 5388234382450264002 |
| 20 | 113692608262971520042 |
| 21 | 2512031106415692960926 |
[0,1,6,32,186,1222,9086,75882,705298,7231862, 81160422,990024466,13047411482,184788881838, 2799459801742,45178128866282,773829771302946, 14021761172671462,267991492197471158, 5388234382450264002,113692608262971520042, 2512031106415692960926] |