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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 28 |
| 3 | 176 |
| 4 | 1240 |
| 5 | 9752 |
| 6 | 85120 |
| 7 | 819296 |
| 8 | 8639872 |
| 9 | 99209600 |
| 10 | 1233416704 |
| 11 | 16517058560 |
| 12 | 237137769472 |
| 13 | 3634932675584 |
| 14 | 59263206154240 |
| 15 | 1024222802014208 |
| 16 | 18706559855656960 |
| 17 | 360062627304341504 |
| 18 | 7285354765603176448 |
[1,5,28,176,1240,9752,85120,819296,8639872, 99209600,1233416704,16517058560,237137769472, 3634932675584,59263206154240,1024222802014208, 18706559855656960,360062627304341504, 7285354765603176448] |