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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 14 |
| 5 | 38 |
| 6 | 127 |
| 7 | 411 |
| 8 | 1492 |
| 9 | 6478 |
| 10 | 27635 |
| 11 | 130093 |
| 12 | 695563 |
| 13 | 3762131 |
| 14 | 21947993 |
| 15 | 141325992 |
| 16 | 926081758 |
| 17 | 6469911674 |
| 18 | 48818612195 |
[1,2,6,14,38,127,411,1492,6478,27635,130093, 695563,3762131,21947993,141325992,926081758, 6469911674,48818612195] |