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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 24 |
| 5 | 89 |
| 6 | 415 |
| 7 | 2372 |
| 8 | 16072 |
| 9 | 125673 |
| 10 | 1112083 |
| 11 | 10976184 |
| 12 | 119481296 |
| 13 | 1421542641 |
| 14 | 18348340127 |
| 15 | 255323504932 |
| 16 | 3809950977008 |
| 17 | 60683990530225 |
| 18 | 1027542662934915 |
| 19 | 18430998766219336 |
| 20 | 349096664728623336 |
| 21 | 6962409983976703337 |
| 22 | 145841989688186383359 |
| 23 | 3201192743180799343844 |
[0,1,3,8,24,89,415,2372,16072,125673,1112083, 10976184,119481296,1421542641,18348340127, 255323504932,3809950977008,60683990530225, 1027542662934915,18430998766219336, 349096664728623336,6962409983976703337, 145841989688186383359,3201192743180799343844] |