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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 25 |
| 4 | 100 |
| 5 | 412 |
| 6 | 1770 |
| 7 | 7757 |
| 8 | 34715 |
| 9 | 157340 |
| 10 | 721929 |
| 11 | 3340801 |
| 12 | 15582566 |
| 13 | 73129582 |
| 14 | 345078964 |
| 15 | 1635861836 |
| 16 | 7785924688 |
| 17 | 37188831495 |
| 18 | 178173911708 |
| 19 | 856008810970 |
| 20 | 4122545235871 |
| 21 | 19898003323666 |
| 22 | 96229368799540 |
| 23 | 466210250864806 |
| 24 | 2262351350838510 |
| 25 | 10994593882046659 |
| 26 | 53503978995352478 |
| 27 | 260693768734287260 |
[1,2,7,25,100,412,1770,7757,34715,157340,721929, 3340801,15582566,73129582,345078964,1635861836, 7785924688,37188831495,178173911708,856008810970, 4122545235871,19898003323666,96229368799540, 466210250864806,2262351350838510, 10994593882046659,53503978995352478, 260693768734287260] |