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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 28 |
| 4 | 270 |
| 5 | 496 |
| 6 | 672 |
| 7 | 1638 |
| 8 | 6200 |
| 9 | 8128 |
| 10 | 18620 |
| 11 | 30240 |
| 12 | 32760 |
| 13 | 173600 |
| 14 | 1089270 |
| 15 | 2229500 |
| 16 | 2457000 |
| 17 | 4713984 |
| 18 | 6051500 |
| 19 | 8506400 |
| 20 | 17428320 |
| 21 | 23088800 |
| 22 | 29410290 |
| 23 | 33550336 |
| 24 | 45532800 |
| 25 | 52141320 |
| 26 | 81695250 |
| 27 | 115048440 |
| 28 | 142990848 |
| 29 | 255428096 |
[1,6,28,270,496,672,1638,6200,8128,18620,30240, 32760,173600,1089270,2229500,2457000,4713984, 6051500,8506400,17428320,23088800,29410290, 33550336,45532800,52141320,81695250,115048440, 142990848,255428096] |