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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 64 |
| 6 | 252 |
| 7 | 1460 |
| 8 | 6256 |
| 9 | 39760 |
| 10 | 230056 |
| 11 | 1920152 |
| 12 | 12154416 |
| 13 | 113087888 |
| 14 | 916563592 |
| 15 | 10586707896 |
| 16 | 80444848064 |
| 17 | 898922718272 |
| 18 | 8634371968224 |
| 19 | 117894609062176 |
| 20 | 1160052513737280 |
| 21 | 16638593775310528 |
| 22 | 200744153681516384 |
| 23 | 3415784055462112160 |
| 24 | 38542918215425934624 |
[1,1,2,6,16,64,252,1460,6256,39760,230056,1920152, 12154416,113087888,916563592,10586707896, 80444848064,898922718272,8634371968224, 117894609062176,1160052513737280, 16638593775310528,200744153681516384, 3415784055462112160,38542918215425934624] |