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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 27 |
| 5 | 180 |
| 6 | 1678 |
| 7 | 20388 |
| 8 | 305331 |
| 9 | 5423511 |
| 10 | 111282445 |
| 11 | 2587931469 |
| 12 | 67239205808 |
| 13 | 1929910531883 |
| 14 | 60636166356164 |
| 15 | 2069775112992573 |
| 16 | 76268207153351225 |
| 17 | 3017346008698599752 |
| 18 | 127561003043924116908 |
| 19 | 5738904556162964523209 |
| 20 | 273764048456544759900846 |
| 21 | 13802374108958236134168506 |
| 22 | 733335098861491664742838394 |
| 23 | 40953333749038944871704984923 |
| 24 | 2398217239830108487402017089693 |
| 25 | 146949291558772355319517897103987 |
[1,1,2,6,27,180,1678,20388,305331,5423511, 111282445,2587931469,67239205808,1929910531883, 60636166356164,2069775112992573,76268207153351225, 3017346008698599752,127561003043924116908, 5738904556162964523209,273764048456544759900846, 13802374108958236134168506, 733335098861491664742838394, 40953333749038944871704984923, 2398217239830108487402017089693, 146949291558772355319517897103987] |