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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 10 |
| 6 | 24 |
| 7 | 70 |
| 8 | 192 |
| 9 | 576 |
| 10 | 1890 |
| 11 | 6300 |
| 12 | 21600 |
| 13 | 78624 |
| 14 | 294840 |
| 15 | 1140480 |
| 16 | 4561920 |
| 17 | 18849600 |
| 18 | 79968000 |
| 19 | 348566400 |
| 20 | 1559376000 |
| 21 | 7147140000 |
| 22 | 33522128640 |
| 23 | 160745472000 |
| 24 | 787652812800 |
| 25 | 3938264064000 |
| 26 | 20080974513600 |
| 27 | 104348244639744 |
| 28 | 552160113120000 |
| 29 | 2973491173785600 |
| 30 | 16286186592000000 |
| 31 | 90678987245246400 |
[1,1,2,4,10,24,70,192,576,1890,6300,21600,78624, 294840,1140480,4561920,18849600,79968000, 348566400,1559376000,7147140000,33522128640, 160745472000,787652812800,3938264064000, 20080974513600,104348244639744,552160113120000, 2973491173785600,16286186592000000, 90678987245246400] |