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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 22 |
| 4 | 150 |
| 5 | 1370 |
| 6 | 14112 |
| 7 | 169884 |
| 8 | 2301264 |
| 9 | 34903584 |
| 10 | 584575200 |
| 11 | 10728401760 |
| 12 | 214047774720 |
| 13 | 4614042856320 |
| 14 | 106866549054720 |
| 15 | 2646889430976000 |
| 16 | 69814736722483200 |
| 17 | 1953778728154982400 |
| 18 | 57822137143219814400 |
| 19 | 1804373878844546150400 |
| 20 | 59213693468692224000000 |
[1,3,22,150,1370,14112,169884,2301264,34903584, 584575200,10728401760,214047774720,4614042856320, 106866549054720,2646889430976000, 69814736722483200,1953778728154982400, 57822137143219814400,1804373878844546150400, 59213693468692224000000] |