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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 16 |
| 3 | 45 |
| 4 | 132 |
| 5 | 449 |
| 6 | 1816 |
| 7 | 8460 |
| 8 | 43717 |
| 9 | 244869 |
| 10 | 1469094 |
| 11 | 9375888 |
| 12 | 63337464 |
| 13 | 451011317 |
| 14 | 3372983491 |
| 15 | 26409145110 |
| 16 | 215868629023 |
| 17 | 1837579724641 |
| 18 | 16254473067368 |
| 19 | 149114870667176 |
| 20 | 1416212525570460 |
| 21 | 13902957827280263 |
[1,5,16,45,132,449,1816,8460,43717,244869,1469094, 9375888,63337464,451011317,3372983491,26409145110, 215868629023,1837579724641,16254473067368, 149114870667176,1416212525570460, 13902957827280263] |