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| n | a(n) |
|---|---|
| 9 | 1 |
| 10 | 20 |
| 11 | 440 |
| 12 | 9680 |
| 13 | 220220 |
| 14 | 5229224 |
| 15 | 130069940 |
| 16 | 3392692160 |
| 17 | 92780281880 |
| 18 | 2657929522820 |
| 19 | 79670485645608 |
| 20 | 2495398380120360 |
| 21 | 81558207395885220 |
| 22 | 2777643033619233780 |
| 23 | 98440545801322467600 |
| 24 | 3625667341827832048176 |
| 25 | 138601954935720474004950 |
| 26 | 5492809832014657114548300 |
[1,20,440,9680,220220,5229224,130069940, 3392692160,92780281880,2657929522820, 79670485645608,2495398380120360,81558207395885220, 2777643033619233780,98440545801322467600, 3625667341827832048176,138601954935720474004950, 5492809832014657114548300] |