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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 756 |
| 3 | 20412 |
| 4 | 551124 |
| 5 | 14880348 |
| 6 | 401769396 |
| 7 | 10847773692 |
| 8 | 292889889684 |
| 9 | 7908027021090 |
| 10 | 213516729559224 |
| 11 | 5764951697823864 |
| 12 | 155653695833814360 |
| 13 | 4202649787312378584 |
| 14 | 113471544252017775096 |
| 15 | 3063731694658235867448 |
[1,28,756,20412,551124,14880348,401769396, 10847773692,292889889684,7908027021090, 213516729559224,5764951697823864, 155653695833814360,4202649787312378584, 113471544252017775096,3063731694658235867448] |