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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 22 |
| 5 | 190 |
| 6 | 1170 |
| 7 | 11646 |
| 8 | 109520 |
| 9 | 1289168 |
| 10 | 16018064 |
| 11 | 223757840 |
| 12 | 3407971488 |
| 13 | 55709905056 |
| 14 | 998011344928 |
| 15 | 18778681069024 |
| 16 | 385316251841536 |
| 17 | 8225863823985664 |
| 18 | 189755182485906432 |
| 19 | 4538893733746003968 |
| 20 | 116147781156885837824 |
| 21 | 3078530007519830730752 |
| 22 | 86521073899573883088896 |
[1,1,1,7,22,190,1170,11646,109520,1289168, 16018064,223757840,3407971488,55709905056, 998011344928,18778681069024,385316251841536, 8225863823985664,189755182485906432, 4538893733746003968,116147781156885837824, 3078530007519830730752,86521073899573883088896] |