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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 15 |
| 6 | 72 |
| 7 | 420 |
| 8 | 2915 |
| 9 | 24570 |
| 10 | 245070 |
| 11 | 2633400 |
| 12 | 30588783 |
| 13 | 383841315 |
| 14 | 5197243590 |
| 15 | 75666140550 |
| 16 | 1177491151785 |
| 17 | 19496256883740 |
| 18 | 342184849138188 |
| 19 | 6346249258076280 |
| 20 | 124023565540658025 |
| 21 | 2547445128977720475 |
| 22 | 54865546632888272820 |
[1,0,0,0,1,15,72,420,2915,24570,245070,2633400, 30588783,383841315,5197243590,75666140550, 1177491151785,19496256883740,342184849138188, 6346249258076280,124023565540658025, 2547445128977720475,54865546632888272820] |