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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 31 |
| 2 | 930 |
| 3 | 27900 |
| 4 | 837000 |
| 5 | 25110000 |
| 6 | 753300000 |
| 7 | 22598999535 |
| 8 | 677969972100 |
| 9 | 20339098744965 |
| 10 | 610172949807900 |
| 11 | 18305188118005500 |
| 12 | 549155632253220000 |
| 13 | 16474668628988250000 |
| 14 | 494240048711397215760 |
| 15 | 14827201156594414216125 |
[1,31,930,27900,837000,25110000,753300000, 22598999535,677969972100,20339098744965, 610172949807900,18305188118005500, 549155632253220000,16474668628988250000, 494240048711397215760,14827201156594414216125] |