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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 4 |
| 3 | 8 |
| 4 | 38 |
| 5 | 90 |
| 6 | 305 |
| 7 | 902 |
| 8 | 2710 |
| 9 | 8376 |
| 10 | 25226 |
| 11 | 77145 |
| 12 | 235122 |
| 13 | 715882 |
| 14 | 2186483 |
| 15 | 6666846 |
| 16 | 20353268 |
| 17 | 62140942 |
| 18 | 189739429 |
| 19 | 579567532 |
| 20 | 1770391431 |
| 21 | 5409031357 |
| 22 | 16528102350 |
| 23 | 50508922108 |
| 24 | 154369025240 |
| 25 | 471828803722 |
| 26 | 1442250315610 |
| 27 | 4408832591287 |
[4,4,8,38,90,305,902,2710,8376,25226,77145,235122, 715882,2186483,6666846,20353268,62140942, 189739429,579567532,1770391431,5409031357, 16528102350,50508922108,154369025240,471828803722, 1442250315610,4408832591287] |