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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 39 |
| 3 | 254 |
| 4 | 1501 |
| 5 | 7502 |
| 6 | 31125 |
| 7 | 111564 |
| 8 | 356666 |
| 9 | 1041746 |
| 10 | 2828429 |
| 11 | 7227752 |
| 12 | 17541293 |
| 13 | 40706954 |
| 14 | 90804704 |
| 15 | 195525484 |
| 16 | 407797895 |
| 17 | 826187028 |
| 18 | 1629896763 |
| 19 | 3137605666 |
| 20 | 5904488589 |
| 21 | 10879371862 |
| 22 | 19655065895 |
| 23 | 34860900004 |
| 24 | 60769196108 |
| 25 | 104219292070 |
[6,39,254,1501,7502,31125,111564,356666,1041746, 2828429,7227752,17541293,40706954,90804704, 195525484,407797895,826187028,1629896763, 3137605666,5904488589,10879371862,19655065895, 34860900004,60769196108,104219292070] |