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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 15 |
| 5 | 44 |
| 6 | 485 |
| 7 | 1854 |
| 8 | 25781 |
| 9 | 170288 |
| 10 | 2477485 |
| 11 | 12571140 |
| 12 | 435748665 |
| 13 | 2049818198 |
| 14 | 64651106637 |
| 15 | 628176476186 |
| 16 | 18837010964105 |
| 17 | 93248340364152 |
| 18 | 6695745240354169 |
| 19 | 33794005826851192 |
| 20 | 2549048418922818525 |
| 21 | 20209158430316698922 |
| 22 | 1138228671555859916609 |
[1,1,1,2,15,44,485,1854,25781,170288,2477485, 12571140,435748665,2049818198,64651106637, 628176476186,18837010964105,93248340364152, 6695745240354169,33794005826851192, 2549048418922818525,20209158430316698922, 1138228671555859916609] |