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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 16 |
| 3 | 72 |
| 4 | 256 |
| 5 | 800 |
| 6 | 2304 |
| 7 | 6272 |
| 8 | 16384 |
| 9 | 41472 |
| 10 | 102400 |
| 11 | 247808 |
| 12 | 589824 |
| 13 | 1384448 |
| 14 | 3211264 |
| 15 | 7372800 |
| 16 | 16777216 |
| 17 | 37879808 |
| 18 | 84934656 |
| 19 | 189267968 |
| 20 | 419430400 |
| 21 | 924844032 |
| 22 | 2030043136 |
| 23 | 4437573632 |
| 24 | 9663676416 |
| 25 | 20971520000 |
| 26 | 45365592064 |
| 27 | 97844723712 |
| 28 | 210453397504 |
[0,2,16,72,256,800,2304,6272,16384,41472,102400, 247808,589824,1384448,3211264,7372800,16777216, 37879808,84934656,189267968,419430400,924844032, 2030043136,4437573632,9663676416,20971520000, 45365592064,97844723712,210453397504] |