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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 17 |
| 5 | 48 |
| 6 | 149 |
| 7 | 477 |
| 8 | 1579 |
| 9 | 5339 |
| 10 | 18375 |
| 11 | 64125 |
| 12 | 226387 |
| 13 | 807025 |
| 14 | 2900827 |
| 15 | 10501870 |
| 16 | 38258497 |
| 17 | 140146660 |
| 18 | 515897197 |
| 19 | 1907409850 |
| 20 | 7080017617 |
| 21 | 26373676870 |
| 22 | 98562581257 |
| 23 | 369433290520 |
| 24 | 1388466728581 |
| 25 | 5231379691972 |
[1,1,3,6,17,48,149,477,1579,5339,18375,64125, 226387,807025,2900827,10501870,38258497,140146660, 515897197,1907409850,7080017617,26373676870, 98562581257,369433290520,1388466728581, 5231379691972] |