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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 130 |
| 4 | 390 |
| 5 | 585 |
| 6 | 3250 |
| 7 | 31980 |
| 8 | 133250 |
| 9 | 223860 |
| 10 | 799500 |
| 11 | 7195500 |
| 12 | 13591500 |
| 13 | 122323500 |
| 14 | 258238500 |
| 15 | 394153500 |
| 16 | 405346500 |
| 17 | 910630500 |
| 18 | 1345558500 |
| 19 | 2025133500 |
| 20 | 8195674500 |
[1,5,130,390,585,3250,31980,133250,223860,799500, 7195500,13591500,122323500,258238500,394153500, 405346500,910630500,1345558500,2025133500, 8195674500] |