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| n | a(n) |
|---|---|
| 3 | 5 |
| 4 | 40 |
| 5 | 220 |
| 6 | 1040 |
| 7 | 4550 |
| 8 | 19040 |
| 9 | 77448 |
| 10 | 308640 |
| 11 | 1209450 |
| 12 | 4668400 |
| 13 | 17766892 |
| 14 | 66718288 |
| 15 | 247397150 |
| 16 | 906584000 |
| 17 | 3285842960 |
| 18 | 11788924992 |
| 19 | 41902786770 |
| 20 | 147668053200 |
| 21 | 516315206260 |
| 22 | 1792304871280 |
| 23 | 6180666260230 |
| 24 | 21184488791840 |
| 25 | 72205377800600 |
| 26 | 244837696095200 |
[5,40,220,1040,4550,19040,77448,308640,1209450, 4668400,17766892,66718288,247397150,906584000, 3285842960,11788924992,41902786770,147668053200, 516315206260,1792304871280,6180666260230, 21184488791840,72205377800600,244837696095200] |