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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 34 |
| 3 | 504 |
| 4 | 10572 |
| 5 | 285408 |
| 6 | 9419440 |
| 7 | 367571200 |
| 8 | 16562241744 |
| 9 | 846509123520 |
| 10 | 48401180913824 |
| 11 | 3061687935718272 |
| 12 | 212316590908782336 |
| 13 | 16018267935253721088 |
| 14 | 1306322033185206970368 |
| 15 | 114519518777575592865792 |
| 16 | 10740222055670467832259840 |
| 17 | 1073051903942317493993088000 |
[1,4,34,504,10572,285408,9419440,367571200, 16562241744,846509123520,48401180913824, 3061687935718272,212316590908782336, 16018267935253721088,1306322033185206970368, 114519518777575592865792, 10740222055670467832259840, 1073051903942317493993088000] |