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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 20 |
| 4 | 160 |
| 5 | 1130 |
| 6 | 8927 |
| 7 | 71630 |
| 8 | 594405 |
| 9 | 5025740 |
| 10 | 43243674 |
| 11 | 377127756 |
| 12 | 3327001441 |
| 13 | 29634744950 |
| 14 | 266164547110 |
| 15 | 2407763862342 |
| 16 | 21918167505714 |
| 17 | 200631620380132 |
| 18 | 1845576127894008 |
| 19 | 17052050519557200 |
| 20 | 158176470846492722 |
[0,5,20,160,1130,8927,71630,594405,5025740, 43243674,377127756,3327001441,29634744950, 266164547110,2407763862342,21918167505714, 200631620380132,1845576127894008, 17052050519557200,158176470846492722] |