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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 14 |
| 5 | 35 |
| 6 | 97 |
| 7 | 264 |
| 8 | 727 |
| 9 | 2059 |
| 10 | 5876 |
| 11 | 16893 |
| 12 | 49085 |
| 13 | 143639 |
| 14 | 422764 |
| 15 | 1251642 |
| 16 | 3724276 |
| 17 | 11129680 |
| 18 | 33393998 |
| 19 | 100560903 |
| 20 | 303812039 |
| 21 | 920617337 |
| 22 | 2797335154 |
| 23 | 8521230447 |
| 24 | 26017690537 |
| 25 | 79610304979 |
| 26 | 244082395820 |
| 27 | 749739211746 |
| 28 | 2306942230064 |
[1,2,6,14,35,97,264,727,2059,5876,16893,49085, 143639,422764,1251642,3724276,11129680,33393998, 100560903,303812039,920617337,2797335154, 8521230447,26017690537,79610304979,244082395820, 749739211746,2306942230064] |