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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 32 |
| 5 | 220 |
| 6 | 1812 |
| 7 | 17108 |
| 8 | 180512 |
| 9 | 2093760 |
| 10 | 26396160 |
| 11 | 358741328 |
| 12 | 5223336288 |
| 13 | 81079811280 |
| 14 | 1336407320080 |
| 15 | 23311138957200 |
| 16 | 429063111959808 |
| 17 | 8311760620707648 |
| 18 | 169072470759431232 |
| 19 | 3603666131945918144 |
| 20 | 80327823251439861760 |
| 21 | 1869212211081119135616 |
| 22 | 45331401566332423284864 |
| 23 | 1143967734536203174726784 |
| 24 | 29996686272924492809481216 |
| 25 | 816185909551276017516640000 |
[1,2,6,32,220,1812,17108,180512,2093760,26396160, 358741328,5223336288,81079811280,1336407320080, 23311138957200,429063111959808,8311760620707648, 169072470759431232,3603666131945918144, 80327823251439861760,1869212211081119135616, 45331401566332423284864,1143967734536203174726784, 29996686272924492809481216, 816185909551276017516640000] |