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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 12 |
| 3 | 60 |
| 4 | 224 |
| 5 | 720 |
| 6 | 2112 |
| 7 | 5824 |
| 8 | 15360 |
| 9 | 39168 |
| 10 | 97280 |
| 11 | 236544 |
| 12 | 565248 |
| 13 | 1331200 |
| 14 | 3096576 |
| 15 | 7127040 |
| 16 | 16252928 |
| 17 | 36765696 |
| 18 | 82575360 |
| 19 | 184287232 |
| 20 | 408944640 |
| 21 | 902823936 |
| 22 | 1983905792 |
| 23 | 4341104640 |
| 24 | 9462349824 |
| 25 | 20552089600 |
| 26 | 44493176832 |
| 27 | 96032784384 |
| 28 | 206695301120 |
| 29 | 443723808768 |
[0,1,12,60,224,720,2112,5824,15360,39168,97280, 236544,565248,1331200,3096576,7127040,16252928, 36765696,82575360,184287232,408944640,902823936, 1983905792,4341104640,9462349824,20552089600, 44493176832,96032784384,206695301120,443723808768] |