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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 378 |
| 3 | 3276 |
| 4 | 20475 |
| 5 | 98280 |
| 6 | 376740 |
| 7 | 1184040 |
| 8 | 3108105 |
| 9 | 6906900 |
| 10 | 13123110 |
| 11 | 21474180 |
| 12 | 30421755 |
| 13 | 37442160 |
| 14 | 40116600 |
| 15 | 37442160 |
| 16 | 30421755 |
| 17 | 21474180 |
| 18 | 13123110 |
| 19 | 6906900 |
| 20 | 3108105 |
| 21 | 1184040 |
| 22 | 376740 |
| 23 | 98280 |
| 24 | 20475 |
| 25 | 3276 |
| 26 | 378 |
| 27 | 28 |
| 28 | 1 |
[1,28,378,3276,20475,98280,376740,1184040,3108105, 6906900,13123110,21474180,30421755,37442160, 40116600,37442160,30421755,21474180,13123110, 6906900,3108105,1184040,376740,98280,20475,3276, 378,28,1] |