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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 8 |
| 7 | 60 |
| 8 | 294 |
| 9 | 1180 |
| 10 | 4200 |
| 11 | 13776 |
| 12 | 42560 |
| 13 | 125568 |
| 14 | 357120 |
| 15 | 985600 |
| 16 | 2652672 |
| 17 | 6988800 |
| 18 | 18077696 |
| 19 | 46018560 |
| 20 | 115507200 |
| 21 | 286326784 |
| 22 | 701890560 |
| 23 | 1703411712 |
| 24 | 4096655360 |
| 25 | 9771417600 |
| 26 | 23132110848 |
| 27 | 54384394240 |
| 28 | 127049662464 |
| 29 | 295069286400 |
| 30 | 681574400000 |
[0,0,0,0,0,0,8,60,294,1180,4200,13776,42560, 125568,357120,985600,2652672,6988800,18077696, 46018560,115507200,286326784,701890560,1703411712, 4096655360,9771417600,23132110848,54384394240, 127049662464,295069286400,681574400000] |