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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 25 |
| 4 | 80 |
| 5 | 225 |
| 6 | 605 |
| 7 | 1600 |
| 8 | 4205 |
| 9 | 11025 |
| 10 | 28880 |
| 11 | 75625 |
| 12 | 198005 |
| 13 | 518400 |
| 14 | 1357205 |
| 15 | 3553225 |
| 16 | 9302480 |
| 17 | 24354225 |
| 18 | 63760205 |
| 19 | 166926400 |
| 20 | 437019005 |
| 21 | 1144130625 |
| 22 | 2995372880 |
| 23 | 7841988025 |
| 24 | 20530591205 |
| 25 | 53749785600 |
| 26 | 140718765605 |
| 27 | 368406511225 |
| 28 | 964500768080 |
[0,5,25,80,225,605,1600,4205,11025,28880,75625, 198005,518400,1357205,3553225,9302480,24354225, 63760205,166926400,437019005,1144130625, 2995372880,7841988025,20530591205,53749785600, 140718765605,368406511225,964500768080] |