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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 79 |
| 4 | 693 |
| 5 | 6079 |
| 6 | 53325 |
| 7 | 467767 |
| 8 | 4103253 |
| 9 | 35993743 |
| 10 | 315737181 |
| 11 | 2769647143 |
| 12 | 24295349925 |
| 13 | 213118855039 |
| 14 | 1869478995501 |
| 15 | 16399073249431 |
| 16 | 143852701253877 |
| 17 | 1261876164786031 |
| 18 | 11069180080566525 |
| 19 | 97098868395526663 |
| 20 | 851751455398606917 |
| 21 | 7471565361796408927 |
[0,1,9,79,693,6079,53325,467767,4103253,35993743, 315737181,2769647143,24295349925,213118855039, 1869478995501,16399073249431,143852701253877, 1261876164786031,11069180080566525, 97098868395526663,851751455398606917, 7471565361796408927] |