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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 64 |
| 4 | 735 |
| 5 | 9276 |
| 6 | 124936 |
| 7 | 1753074 |
| 8 | 25366335 |
| 9 | 375677659 |
| 10 | 5667212132 |
| 11 | 86775157140 |
| 12 | 1345153548264 |
| 13 | 21069043965984 |
| 14 | 332927800269694 |
| 15 | 5301031234085664 |
| 16 | 84967018635587775 |
| 17 | 1369846562874360887 |
| 18 | 22199151536133457885 |
| 19 | 361411377745122110422 |
| 20 | 5908312923795257331460 |
[1,1,7,64,735,9276,124936,1753074,25366335, 375677659,5667212132,86775157140,1345153548264, 21069043965984,332927800269694,5301031234085664, 84967018635587775,1369846562874360887, 22199151536133457885,361411377745122110422, 5908312923795257331460] |