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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 10 |
| 3 | 45 |
| 4 | 216 |
| 5 | 1528 |
| 6 | 11728 |
| 7 | 66372 |
| 8 | 403920 |
| 9 | 2587588 |
| 10 | 16422928 |
| 11 | 100924052 |
| 12 | 627229368 |
| 13 | 3931197172 |
| 14 | 24518011160 |
| 15 | 152485541704 |
| 16 | 950191656704 |
| 17 | 5926384223020 |
| 18 | 36928044675096 |
| 19 | 230056295804064 |
| 20 | 1433703853124720 |
[0,10,45,216,1528,11728,66372,403920,2587588, 16422928,100924052,627229368,3931197172, 24518011160,152485541704,950191656704, 5926384223020,36928044675096,230056295804064, 1433703853124720] |