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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 20 |
| 5 | 62 |
| 6 | 193 |
| 7 | 608 |
| 8 | 1918 |
| 9 | 6061 |
| 10 | 19160 |
| 11 | 60582 |
| 12 | 191568 |
| 13 | 605782 |
| 14 | 1915640 |
| 15 | 6057776 |
| 16 | 19156359 |
| 17 | 60577716 |
| 18 | 191563545 |
| 19 | 605777108 |
| 20 | 1915635402 |
[1,2,7,20,62,193,608,1918,6061,19160,60582,191568, 605782,1915640,6057776,19156359,60577716, 191563545,605777108,1915635402] |