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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 28 |
| 4 | 120 |
| 5 | 228 |
| 6 | 496 |
| 7 | 672 |
| 8 | 8128 |
| 9 | 30240 |
| 10 | 32760 |
| 11 | 125640 |
| 12 | 501888 |
| 13 | 523776 |
| 14 | 1207944 |
| 15 | 2178540 |
| 16 | 23569920 |
| 17 | 29720448 |
| 18 | 33550336 |
| 19 | 45532800 |
| 20 | 142990848 |
| 21 | 459818240 |
| 22 | 1379454720 |
| 23 | 1476304896 |
| 24 | 8589869056 |
| 25 | 14182439040 |
| 26 | 31998395520 |
| 27 | 43861478400 |
| 28 | 51001180160 |
[1,6,28,120,228,496,672,8128,30240,32760,125640, 501888,523776,1207944,2178540,23569920,29720448, 33550336,45532800,142990848,459818240,1379454720, 1476304896,8589869056,14182439040,31998395520, 43861478400,51001180160] |