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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 2520 |
| 8 | 9240 |
| 9 | 35490 |
| 10 | 142758 |
| 11 | 601167 |
| 12 | 2648967 |
| 13 | 10532752 |
| 14 | 42054602 |
| 15 | 168941427 |
| 16 | 684260967 |
| 17 | 2800315185 |
| 18 | 11604074418 |
| 19 | 47073995851 |
| 20 | 190962943230 |
| 21 | 775113276195 |
| 22 | 3150369602031 |
| 23 | 12833577676317 |
| 24 | 52456318079954 |
| 25 | 213463250487565 |
[1,2,6,24,120,720,2520,9240,35490,142758,601167, 2648967,10532752,42054602,168941427,684260967, 2800315185,11604074418,47073995851,190962943230, 775113276195,3150369602031,12833577676317, 52456318079954,213463250487565] |