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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 8 |
| 3 | 54 |
| 4 | 256 |
| 5 | 1050 |
| 6 | 3984 |
| 7 | 14406 |
| 8 | 50432 |
| 9 | 172530 |
| 10 | 580240 |
| 11 | 1926078 |
| 12 | 6328128 |
| 13 | 20619690 |
| 14 | 66732176 |
| 15 | 214742070 |
| 16 | 687698944 |
| 17 | 2193154530 |
| 18 | 6968850192 |
| 19 | 22073006382 |
| 20 | 69714716480 |
| 21 | 219623377050 |
| 22 | 690291036688 |
| 23 | 2165100175014 |
[0,0,8,54,256,1050,3984,14406,50432,172530,580240, 1926078,6328128,20619690,66732176,214742070, 687698944,2193154530,6968850192,22073006382, 69714716480,219623377050,690291036688, 2165100175014] |