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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 522 |
| 5 | 34986 |
| 6 | 4524240 |
| 7 | 1003172616 |
| 8 | 351349509504 |
| 9 | 182985164256000 |
| 10 | 135303274820730372 |
| 11 | 136936922140937021688 |
| 12 | 184146557651652262521738 |
| 13 | 321051865325352021467189658 |
| 14 | 710866983641078174204266934736 |
| 15 | 1964068265459581480020247325821224 |
[1,1,2,18,522,34986,4524240,1003172616, 351349509504,182985164256000,135303274820730372, 136936922140937021688,184146557651652262521738, 321051865325352021467189658, 710866983641078174204266934736, 1964068265459581480020247325821224] |