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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 48 |
| 5 | 160 |
| 6 | 480 |
| 7 | 1344 |
| 8 | 3584 |
| 9 | 9216 |
| 10 | 23040 |
| 11 | 56320 |
| 12 | 135168 |
| 13 | 319488 |
| 14 | 745472 |
| 15 | 1720320 |
| 16 | 3932160 |
| 17 | 8912896 |
| 18 | 20054016 |
| 19 | 44826624 |
| 20 | 99614720 |
| 21 | 220200960 |
| 22 | 484442112 |
| 23 | 1061158912 |
| 24 | 2315255808 |
| 25 | 5033164800 |
| 26 | 10905190400 |
| 27 | 23555211264 |
| 28 | 50734301184 |
| 29 | 108984795136 |
[0,0,2,12,48,160,480,1344,3584,9216,23040,56320, 135168,319488,745472,1720320,3932160,8912896, 20054016,44826624,99614720,220200960,484442112, 1061158912,2315255808,5033164800,10905190400, 23555211264,50734301184,108984795136] |