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| n | a(n) |
|---|---|
| 10 | 2 |
| 11 | 40 |
| 12 | 698 |
| 13 | 11908 |
| 14 | 206388 |
| 15 | 3690960 |
| 16 | 68577600 |
| 17 | 1327697280 |
| 18 | 26812356480 |
| 19 | 564796979240 |
| 20 | 12403183337690 |
| 21 | 283718956204402 |
| 22 | 6753363090218970 |
| 23 | 167092903876164794 |
| 24 | 4292602805804464576 |
| 25 | 114374394103260000000 |
| 26 | 3157276569203744863200 |
| 27 | 90202107365906127228000 |
[2,40,698,11908,206388,3690960,68577600, 1327697280,26812356480,564796979240, 12403183337690,283718956204402,6753363090218970, 167092903876164794,4292602805804464576, 114374394103260000000,3157276569203744863200, 90202107365906127228000] |