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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 28 |
| 4 | 55 |
| 5 | 286 |
| 6 | 560 |
| 7 | 3060 |
| 8 | 5985 |
| 9 | 33649 |
| 10 | 65780 |
| 11 | 376740 |
| 12 | 736281 |
| 13 | 4272048 |
| 14 | 8347680 |
| 15 | 48903492 |
| 16 | 95548245 |
| 17 | 563921995 |
| 18 | 1101716330 |
| 19 | 6540715896 |
| 20 | 12777711870 |
| 21 | 76223753060 |
| 22 | 148902215280 |
| 23 | 891794789340 |
| 24 | 1742058970275 |
| 25 | 10468434365991 |
[1,3,6,28,55,286,560,3060,5985,33649,65780,376740, 736281,4272048,8347680,48903492,95548245, 563921995,1101716330,6540715896,12777711870, 76223753060,148902215280,891794789340, 1742058970275,10468434365991] |