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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 36 |
| 5 | 666 |
| 6 | 24696 |
| 7 | 1808820 |
| 8 | 259300148 |
| 9 | 72369408510 |
| 10 | 39205936157880 |
| 11 | 41152969216872016 |
| 12 | 83592236529606631688 |
| 13 | 328284931491454739745904 |
| 14 | 2490876950205850778116435156 |
| 15 | 36494758452603010620499864088198 |
| 16 | 1032033208911845667821292289616451218 |
[1,1,4,36,666,24696,1808820,259300148,72369408510, 39205936157880,41152969216872016, 83592236529606631688,328284931491454739745904, 2490876950205850778116435156, 36494758452603010620499864088198, 1032033208911845667821292289616451218] |