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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 16 |
| 3 | 260 |
| 4 | 1096 |
| 5 | 5430 |
| 6 | 15960 |
| 7 | 47432 |
| 8 | 109552 |
| 9 | 246890 |
| 10 | 483520 |
| 11 | 920652 |
| 12 | 1606776 |
| 13 | 2735390 |
| 14 | 4392136 |
| 15 | 6907280 |
| 16 | 10419040 |
| 17 | 15447762 |
| 18 | 22202352 |
| 19 | 31455380 |
| 20 | 43507240 |
| 21 | 59453702 |
| 22 | 79710136 |
| 23 | 105775320 |
| 24 | 138205776 |
| 25 | 178991930 |
| 26 | 228860320 |
| 27 | 290390492 |
[2,16,260,1096,5430,15960,47432,109552,246890, 483520,920652,1606776,2735390,4392136,6907280, 10419040,15447762,22202352,31455380,43507240, 59453702,79710136,105775320,138205776,178991930, 228860320,290390492] |