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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 21 |
| 4 | 91 |
| 5 | 385 |
| 6 | 1837 |
| 7 | 8272 |
| 8 | 39732 |
| 9 | 185592 |
| 10 | 891024 |
| 11 | 4183040 |
| 12 | 20199964 |
| 13 | 95232864 |
| 14 | 456282264 |
| 15 | 2162574984 |
| 16 | 10330196754 |
| 17 | 48834699384 |
| 18 | 232725598884 |
| 19 | 1098684561984 |
| 20 | 5214388065324 |
| 21 | 24591671545164 |
| 22 | 116257200312444 |
| 23 | 546797015443194 |
| 24 | 2578396047478494 |
| 25 | 12098087101521510 |
[1,2,6,21,91,385,1837,8272,39732,185592,891024, 4183040,20199964,95232864,456282264,2162574984, 10330196754,48834699384,232725598884, 1098684561984,5214388065324,24591671545164, 116257200312444,546797015443194,2578396047478494, 12098087101521510] |