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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 36 |
| 4 | 150 |
| 5 | 558 |
| 6 | 2126 |
| 7 | 8480 |
| 8 | 33639 |
| 9 | 131920 |
| 10 | 540025 |
| 11 | 2122564 |
| 12 | 8415455 |
| 13 | 33814594 |
| 14 | 135946810 |
| 15 | 537839881 |
| 16 | 2157395672 |
| 17 | 8623989781 |
| 18 | 34438483139 |
| 19 | 137851777060 |
| 20 | 551209368188 |
| 21 | 2200738232246 |
| 22 | 8832752603844 |
| 23 | 35249999364267 |
| 24 | 140816183400831 |
[4,16,36,150,558,2126,8480,33639,131920,540025, 2122564,8415455,33814594,135946810,537839881, 2157395672,8623989781,34438483139,137851777060, 551209368188,2200738232246,8832752603844, 35249999364267,140816183400831] |