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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 18 |
| 6 | 131 |
| 7 | 1180 |
| 8 | 12570 |
| 9 | 154535 |
| 10 | 2151439 |
| 11 | 33431046 |
| 12 | 573197723 |
| 13 | 10743619285 |
| 14 | 218447494812 |
| 15 | 4787255999220 |
| 16 | 112454930390211 |
| 17 | 2818138438707516 |
| 18 | 75031660452368001 |
| 19 | 2114705500316025737 |
| 20 | 62890323682634277951 |
| 21 | 1967901134191778583146 |
| 22 | 64623905086814216468839 |
[1,1,0,1,3,18,131,1180,12570,154535,2151439, 33431046,573197723,10743619285,218447494812, 4787255999220,112454930390211,2818138438707516, 75031660452368001,2114705500316025737, 62890323682634277951,1967901134191778583146, 64623905086814216468839] |