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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 88 |
| 5 | 481 |
| 6 | 2812 |
| 7 | 16808 |
| 8 | 102988 |
| 9 | 640545 |
| 10 | 4035604 |
| 11 | 25679569 |
| 12 | 164778696 |
| 13 | 1064714401 |
| 14 | 6920652008 |
| 15 | 45214871857 |
| 16 | 296722645888 |
| 17 | 1954878268801 |
| 18 | 12923917765876 |
| 19 | 85705978837393 |
| 20 | 569944761286648 |
| 21 | 3799631728468936 |
| 22 | 25388448380261788 |
| 23 | 169992219503608177 |
| 24 | 1140364472585830196 |
[1,4,17,88,481,2812,16808,102988,640545,4035604, 25679569,164778696,1064714401,6920652008, 45214871857,296722645888,1954878268801, 12923917765876,85705978837393,569944761286648, 3799631728468936,25388448380261788, 169992219503608177,1140364472585830196] |