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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 22 |
| 6 | 88 |
| 7 | 370 |
| 8 | 1607 |
| 9 | 7150 |
| 10 | 32418 |
| 11 | 149246 |
| 12 | 695840 |
| 13 | 3278942 |
| 14 | 15591708 |
| 15 | 74721660 |
| 16 | 360540041 |
| 17 | 1750069638 |
| 18 | 8539926158 |
| 19 | 41869742140 |
| 20 | 206149706634 |
| 21 | 1018875856490 |
| 22 | 5053136206216 |
| 23 | 25140141786040 |
| 24 | 125436643981858 |
[1,1,2,6,22,88,370,1607,7150,32418,149246,695840, 3278942,15591708,74721660,360540041,1750069638, 8539926158,41869742140,206149706634,1018875856490, 5053136206216,25140141786040,125436643981858] |