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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 36 |
| 5 | 125 |
| 6 | 454 |
| 7 | 1716 |
| 8 | 6593 |
| 9 | 25701 |
| 10 | 102083 |
| 11 | 408319 |
| 12 | 1651891 |
| 13 | 6730414 |
| 14 | 27610680 |
| 15 | 113907332 |
| 16 | 472370273 |
| 17 | 1967168204 |
| 18 | 8225197054 |
| 19 | 34508435173 |
| 20 | 145232346024 |
| 21 | 612927899755 |
| 22 | 2593328585776 |
| 23 | 10997662595488 |
| 24 | 46736728652704 |
| 25 | 198998577626392 |
| 26 | 848812543325049 |
| 27 | 3626459868034755 |
[1,1,4,10,36,125,454,1716,6593,25701,102083, 408319,1651891,6730414,27610680,113907332, 472370273,1967168204,8225197054,34508435173, 145232346024,612927899755,2593328585776, 10997662595488,46736728652704,198998577626392, 848812543325049,3626459868034755] |