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| n | a(n) |
|---|---|
| 1 | 220 |
| 2 | 2916 |
| 3 | 20736 |
| 4 | 161604 |
| 5 | 726880 |
| 6 | 4359744 |
| 7 | 15444224 |
| 8 | 78039556 |
| 9 | 238216520 |
| 10 | 1091641600 |
| 11 | 3064541952 |
| 12 | 13194657424 |
| 13 | 35313510072 |
| 14 | 145324113796 |
| 15 | 378585527360 |
| 16 | 1503409490496 |
| 17 | 3856470856448 |
| 18 | 14877667836964 |
| 19 | 37794053212800 |
[220,2916,20736,161604,726880,4359744,15444224, 78039556,238216520,1091641600,3064541952, 13194657424,35313510072,145324113796,378585527360, 1503409490496,3856470856448,14877667836964, 37794053212800] |