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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 30 |
| 2 | 420 |
| 3 | 3640 |
| 4 | 21870 |
| 5 | 96936 |
| 6 | 331240 |
| 7 | 911040 |
| 8 | 2128260 |
| 9 | 4495430 |
| 10 | 8972712 |
| 11 | 16946280 |
| 12 | 29822520 |
| 13 | 49476840 |
| 14 | 80027280 |
| 15 | 127083328 |
| 16 | 193511790 |
| 17 | 282611280 |
| 18 | 409172940 |
| 19 | 590913960 |
| 20 | 825736296 |
| 21 | 1115671760 |
| 22 | 1509537960 |
| 23 | 2048372160 |
| 24 | 2698852520 |
| 25 | 3463029894 |
[1,30,420,3640,21870,96936,331240,911040,2128260, 4495430,8972712,16946280,29822520,49476840, 80027280,127083328,193511790,282611280,409172940, 590913960,825736296,1115671760,1509537960, 2048372160,2698852520,3463029894] |