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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 15 |
| 4 | 232 |
| 5 | 5335 |
| 6 | 175416 |
| 7 | 7847665 |
| 8 | 460083056 |
| 9 | 34295632587 |
| 10 | 3171572232860 |
| 11 | 356568882856505 |
| 12 | 47917706485943520 |
| 13 | 7587855756759594511 |
| 14 | 1398620339344282321232 |
| 15 | 296926334953470628671285 |
| 16 | 71938929865159851175220384 |
| 17 | 19730017662046372201511846043 |
| 18 | 6081674963212598041745828898948 |
| 19 | 2093499393528764015996786711595373 |
| 20 | 800173558940733992481330233586267600 |
[1,0,2,15,232,5335,175416,7847665,460083056, 34295632587,3171572232860,356568882856505, 47917706485943520,7587855756759594511, 1398620339344282321232,296926334953470628671285, 71938929865159851175220384, 19730017662046372201511846043, 6081674963212598041745828898948, 2093499393528764015996786711595373, 800173558940733992481330233586267600] |