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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 8 |
| 6 | 38 |
| 7 | 206 |
| 8 | 1200 |
| 9 | 7034 |
| 10 | 53012 |
| 11 | 465190 |
| 12 | 4072948 |
| 13 | 40967916 |
| 14 | 438348328 |
| 15 | 5113450320 |
| 16 | 63135973560 |
| 17 | 835727519000 |
| 18 | 11736948927176 |
| 19 | 175225673352928 |
| 20 | 2749604628466960 |
| 21 | 45540211979269216 |
| 22 | 791473522065224592 |
| 23 | 14405894145521294480 |
| 24 | 274114459633006310336 |
[1,1,1,4,8,38,206,1200,7034,53012,465190,4072948, 40967916,438348328,5113450320,63135973560, 835727519000,11736948927176,175225673352928, 2749604628466960,45540211979269216, 791473522065224592,14405894145521294480, 274114459633006310336] |