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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 10 |
| 4 | 77 |
| 5 | 546 |
| 6 | 3740 |
| 7 | 25194 |
| 8 | 168245 |
| 9 | 1118260 |
| 10 | 7413705 |
| 11 | 49085400 |
| 12 | 324794316 |
| 13 | 2148789800 |
| 14 | 14217578856 |
| 15 | 94096891658 |
| 16 | 622997471685 |
| 17 | 4126520887720 |
| 18 | 27345271410275 |
| 19 | 181295437422330 |
| 20 | 1202538435463365 |
| 21 | 7980245606038650 |
[0,1,10,77,546,3740,25194,168245,1118260,7413705, 49085400,324794316,2148789800,14217578856, 94096891658,622997471685,4126520887720, 27345271410275,181295437422330,1202538435463365, 7980245606038650] |