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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 60 |
| 4 | 2480 |
| 5 | 242296 |
| 6 | 53763904 |
| 7 | 28363717952 |
| 8 | 41396018951936 |
| 9 | 215328934357721024 |
| 10 | 4740698193856769942528 |
| 11 | 430771050114778618253200384 |
| 12 | 151994706469390446336698323709952 |
[1,1,4,60,2480,242296,53763904,28363717952, 41396018951936,215328934357721024, 4740698193856769942528, 430771050114778618253200384, 151994706469390446336698323709952] |