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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 5 |
| 2 | 45 |
| 3 | 320 |
| 4 | 2205 |
| 5 | 15125 |
| 6 | 103680 |
| 7 | 710645 |
| 8 | 4870845 |
| 9 | 33385280 |
| 10 | 228826125 |
| 11 | 1568397605 |
| 12 | 10749957120 |
| 13 | 73681302245 |
| 14 | 505019158605 |
| 15 | 3461452808000 |
| 16 | 23725150497405 |
| 17 | 162614600673845 |
| 18 | 1114577054219520 |
| 19 | 7639424778862805 |
[0,5,45,320,2205,15125,103680,710645,4870845, 33385280,228826125,1568397605,10749957120, 73681302245,505019158605,3461452808000, 23725150497405,162614600673845,1114577054219520, 7639424778862805] |