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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 19 |
| 2 | 209 |
| 3 | 1710 |
| 4 | 11495 |
| 5 | 66880 |
| 6 | 347681 |
| 7 | 1649637 |
| 8 | 7252300 |
| 9 | 29875505 |
| 10 | 116319938 |
| 11 | 430976031 |
| 12 | 1527928814 |
| 13 | 5206792965 |
| 14 | 17119704425 |
| 15 | 54484060983 |
| 16 | 168297474675 |
| 17 | 505762373795 |
| 18 | 1481733152790 |
| 19 | 4239676354650 |
| 20 | 11866652524496 |
| 21 | 32536693623850 |
[1,19,209,1710,11495,66880,347681,1649637,7252300, 29875505,116319938,430976031,1527928814, 5206792965,17119704425,54484060983,168297474675, 505762373795,1481733152790,4239676354650, 11866652524496,32536693623850] |