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| n | a(n) |
|---|---|
| 2 | 3 |
| 3 | 13 |
| 4 | 45 |
| 5 | 148 |
| 6 | 486 |
| 7 | 1618 |
| 8 | 5478 |
| 9 | 18841 |
| 10 | 65692 |
| 11 | 231713 |
| 12 | 825386 |
| 13 | 2964937 |
| 14 | 10728241 |
| 15 | 39065505 |
| 16 | 143047469 |
| 17 | 526399048 |
| 18 | 1945668327 |
| 19 | 7220164256 |
| 20 | 26889574045 |
| 21 | 100469991084 |
| 22 | 376513308113 |
| 23 | 1414840405426 |
| 24 | 5329942273203 |
| 25 | 20125253091226 |
[3,13,45,148,486,1618,5478,18841,65692,231713, 825386,2964937,10728241,39065505,143047469, 526399048,1945668327,7220164256,26889574045, 100469991084,376513308113,1414840405426, 5329942273203,20125253091226] |