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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 16 |
| 5 | 32 |
| 6 | 144 |
| 7 | 544 |
| 8 | 1664 |
| 9 | 5664 |
| 10 | 17968 |
| 11 | 56096 |
| 12 | 174576 |
| 13 | 533504 |
| 14 | 1618432 |
| 15 | 4870464 |
| 16 | 14545488 |
| 17 | 43184928 |
| 18 | 127499856 |
| 19 | 374584288 |
| 20 | 1095687296 |
| 21 | 3192166752 |
| 22 | 9266416752 |
| 23 | 26810232864 |
| 24 | 77333818800 |
| 25 | 222445402560 |
| 26 | 638195965440 |
| 27 | 1826597535360 |
[0,0,0,16,32,144,544,1664,5664,17968,56096,174576, 533504,1618432,4870464,14545488,43184928, 127499856,374584288,1095687296,3192166752, 9266416752,26810232864,77333818800,222445402560, 638195965440,1826597535360] |