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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 36 |
| 3 | 300 |
| 4 | 1960 |
| 5 | 11340 |
| 6 | 60984 |
| 7 | 312312 |
| 8 | 1544400 |
| 9 | 7438860 |
| 10 | 35103640 |
| 11 | 162954792 |
| 12 | 746347056 |
| 13 | 3380195000 |
| 14 | 15164074800 |
| 15 | 67476121200 |
| 16 | 298135873440 |
| 17 | 1309153089420 |
| 18 | 5717335239000 |
| 19 | 24847720451400 |
| 20 | 107520292479600 |
| 21 | 463440029892840 |
| 22 | 1990477619679120 |
| 23 | 8521600803066000 |
[1,2,36,300,1960,11340,60984,312312,1544400, 7438860,35103640,162954792,746347056,3380195000, 15164074800,67476121200,298135873440, 1309153089420,5717335239000,24847720451400, 107520292479600,463440029892840,1990477619679120, 8521600803066000] |