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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 33 |
| 4 | 280 |
| 5 | 2883 |
| 6 | 34817 |
| 7 | 481477 |
| 8 | 7489454 |
| 9 | 129259662 |
| 10 | 2448516959 |
| 11 | 50460561330 |
| 12 | 1123192711285 |
| 13 | 26838555204646 |
| 14 | 684871918806173 |
| 15 | 18580595826856937 |
| 16 | 533846105922876855 |
| 17 | 16187892824592956798 |
| 18 | 516492582419620294678 |
| 19 | 17292646954057122160416 |
| 20 | 606075769032914504000388 |
[1,1,5,33,280,2883,34817,481477,7489454,129259662, 2448516959,50460561330,1123192711285, 26838555204646,684871918806173,18580595826856937, 533846105922876855,16187892824592956798, 516492582419620294678,17292646954057122160416, 606075769032914504000388] |