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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 14 |
| 3 | 52 |
| 4 | 198 |
| 5 | 764 |
| 6 | 2740 |
| 7 | 10484 |
| 8 | 40696 |
| 9 | 159332 |
| 10 | 627156 |
| 11 | 2382476 |
| 12 | 9325816 |
| 13 | 36745928 |
| 14 | 140449732 |
| 15 | 551401060 |
| 16 | 2177363676 |
| 17 | 8627713732 |
| 18 | 33486205428 |
| 19 | 132260864136 |
| 20 | 524379503740 |
| 21 | 2041541080656 |
| 22 | 8075260485044 |
| 23 | 32050426949496 |
| 24 | 125201330295448 |
[4,14,52,198,764,2740,10484,40696,159332,627156, 2382476,9325816,36745928,140449732,551401060, 2177363676,8627713732,33486205428,132260864136, 524379503740,2041541080656,8075260485044, 32050426949496,125201330295448] |