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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 40 |
| 6 | 153 |
| 7 | 634 |
| 8 | 2785 |
| 9 | 12634 |
| 10 | 58409 |
| 11 | 272738 |
| 12 | 1280233 |
| 13 | 6024682 |
| 14 | 28383609 |
| 15 | 133772018 |
| 16 | 630473513 |
| 17 | 2970963898 |
| 18 | 13996752665 |
| 19 | 65924951490 |
| 20 | 310433985929 |
| 21 | 1461486107146 |
| 22 | 6879181490937 |
| 23 | 32374728610962 |
| 24 | 152339562845289 |
[1,2,4,12,40,153,634,2785,12634,58409,272738, 1280233,6024682,28383609,133772018,630473513, 2970963898,13996752665,65924951490,310433985929, 1461486107146,6879181490937,32374728610962, 152339562845289] |