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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 4 |
| 5 | 20 |
| 6 | 10 |
| 7 | 70 |
| 8 | 56 |
| 9 | 504 |
| 10 | 420 |
| 11 | 4620 |
| 12 | 3960 |
| 13 | 3432 |
| 14 | 6006 |
| 15 | 90090 |
| 16 | 80080 |
| 17 | 1361360 |
| 18 | 408408 |
| 19 | 369512 |
| 20 | 67184 |
| 21 | 470288 |
| 22 | 1293292 |
| 23 | 29745716 |
| 24 | 27457584 |
| 25 | 228813200 |
| 26 | 212469400 |
| 27 | 5736673800 |
| 28 | 5354228880 |
| 29 | 155272637520 |
| 30 | 291136195350 |
| 31 | 273491577450 |
[1,2,6,4,20,10,70,56,504,420,4620,3960,3432,6006, 90090,80080,1361360,408408,369512,67184,470288, 1293292,29745716,27457584,228813200,212469400, 5736673800,5354228880,155272637520,291136195350, 273491577450] |