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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 66 |
| 3 | 1460 |
| 4 | 54850 |
| 5 | 2031252 |
| 6 | 86874564 |
| 7 | 3848298792 |
| 8 | 180295263810 |
| 9 | 8709958973540 |
| 10 | 433617084579316 |
| 11 | 22071658807720392 |
| 12 | 1145600816547477316 |
| 13 | 60423221241495866600 |
| 14 | 3231675487858598367240 |
| 15 | 174928470621208572186960 |
[1,2,66,1460,54850,2031252,86874564,3848298792, 180295263810,8709958973540,433617084579316, 22071658807720392,1145600816547477316, 60423221241495866600,3231675487858598367240, 174928470621208572186960] |