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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 6 |
| 3 | 16 |
| 4 | 34 |
| 5 | 84 |
| 6 | 198 |
| 7 | 480 |
| 8 | 1154 |
| 9 | 2788 |
| 10 | 6726 |
| 11 | 16240 |
| 12 | 39202 |
| 13 | 94644 |
| 14 | 228486 |
| 15 | 551616 |
| 16 | 1331714 |
| 17 | 3215044 |
| 18 | 7761798 |
| 19 | 18738640 |
| 20 | 45239074 |
| 21 | 109216788 |
| 22 | 263672646 |
| 23 | 636562080 |
| 24 | 1536796802 |
| 25 | 3710155684 |
[4,6,16,34,84,198,480,1154,2788,6726,16240,39202, 94644,228486,551616,1331714,3215044,7761798, 18738640,45239074,109216788,263672646,636562080, 1536796802,3710155684] |