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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 16 |
| 5 | 56 |
| 6 | 192 |
| 7 | 624 |
| 8 | 1920 |
| 9 | 5632 |
| 10 | 15872 |
| 11 | 43264 |
| 12 | 114688 |
| 13 | 296960 |
| 14 | 753664 |
| 15 | 1880064 |
| 16 | 4620288 |
| 17 | 11206656 |
| 18 | 26869760 |
| 19 | 63766528 |
| 20 | 149946368 |
| 21 | 349700096 |
| 22 | 809500672 |
| 23 | 1861222400 |
| 24 | 4253024256 |
| 25 | 9663676416 |
| 26 | 21843935232 |
| 27 | 49140465664 |
| 28 | 110058536960 |
| 29 | 245484224512 |
| 30 | 545460846592 |
[1,1,1,16,56,192,624,1920,5632,15872,43264,114688, 296960,753664,1880064,4620288,11206656,26869760, 63766528,149946368,349700096,809500672,1861222400, 4253024256,9663676416,21843935232,49140465664, 110058536960,245484224512,545460846592] |