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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 28 |
| 4 | 88 |
| 5 | 245 |
| 6 | 639 |
| 7 | 1608 |
| 8 | 3968 |
| 9 | 9689 |
| 10 | 23527 |
| 11 | 56964 |
| 12 | 137720 |
| 13 | 332717 |
| 14 | 803519 |
| 15 | 1940176 |
| 16 | 4684352 |
| 17 | 11309425 |
| 18 | 27303815 |
| 19 | 65917740 |
| 20 | 159140056 |
| 21 | 384198693 |
| 22 | 927538367 |
| 23 | 2239276440 |
| 24 | 5406092352 |
| 25 | 13051462345 |
| 26 | 31509018343 |
| 27 | 76069500436 |
[1,7,28,88,245,639,1608,3968,9689,23527,56964, 137720,332717,803519,1940176,4684352,11309425, 27303815,65917740,159140056,384198693,927538367, 2239276440,5406092352,13051462345,31509018343, 76069500436] |