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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 452 |
| 3 | 2608 |
| 4 | 14760 |
| 5 | 84948 |
| 6 | 484400 |
| 7 | 2771648 |
| 8 | 15802528 |
| 9 | 90361616 |
| 10 | 516384576 |
| 11 | 2952092672 |
| 12 | 16860669056 |
| 13 | 96327668544 |
| 14 | 550413844224 |
| 15 | 3145705321472 |
| 16 | 17974353615360 |
| 17 | 102695841511680 |
| 18 | 586762124067840 |
| 19 | 3352875664056320 |
[81,452,2608,14760,84948,484400,2771648,15802528, 90361616,516384576,2952092672,16860669056, 96327668544,550413844224,3145705321472, 17974353615360,102695841511680,586762124067840, 3352875664056320] |