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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 21 |
| 4 | 56 |
| 5 | 178 |
| 6 | 609 |
| 7 | 1997 |
| 8 | 6511 |
| 9 | 21494 |
| 10 | 71021 |
| 11 | 234110 |
| 12 | 771936 |
| 13 | 2546839 |
| 14 | 8401997 |
| 15 | 27715289 |
| 16 | 91426922 |
| 17 | 301604833 |
| 18 | 994943072 |
| 19 | 3282138566 |
| 20 | 10827217153 |
| 21 | 35717165621 |
| 22 | 117824839843 |
| 23 | 388684058778 |
| 24 | 1282202639897 |
| 25 | 4229768507606 |
[1,6,21,56,178,609,1997,6511,21494,71021,234110, 771936,2546839,8401997,27715289,91426922, 301604833,994943072,3282138566,10827217153, 35717165621,117824839843,388684058778, 1282202639897,4229768507606] |