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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 18 |
| 3 | 87 |
| 4 | 364 |
| 5 | 1448 |
| 6 | 5416 |
| 7 | 19836 |
| 8 | 74870 |
| 9 | 262213 |
| 10 | 917960 |
| 11 | 3158943 |
| 12 | 10842201 |
| 13 | 36690183 |
| 14 | 124716138 |
| 15 | 425993118 |
| 16 | 1430648672 |
| 17 | 4749540248 |
| 18 | 15725455165 |
| 19 | 52295020828 |
| 20 | 172195798783 |
| 21 | 568455044734 |
| 22 | 1891544349000 |
| 23 | 6216264579905 |
| 24 | 20327990695444 |
| 25 | 66528129183957 |
[3,18,87,364,1448,5416,19836,74870,262213,917960, 3158943,10842201,36690183,124716138,425993118, 1430648672,4749540248,15725455165,52295020828, 172195798783,568455044734,1891544349000, 6216264579905,20327990695444,66528129183957] |