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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 8 |
| 3 | 24 |
| 4 | 64 |
| 5 | 156 |
| 6 | 358 |
| 7 | 786 |
| 8 | 1664 |
| 9 | 3434 |
| 10 | 6902 |
| 11 | 13656 |
| 12 | 26464 |
| 13 | 50772 |
| 14 | 95754 |
| 15 | 179442 |
| 16 | 331294 |
| 17 | 609496 |
| 18 | 1106106 |
| 19 | 2004852 |
| 20 | 3586874 |
| 21 | 6423028 |
| 22 | 11351274 |
| 23 | 20126538 |
| 24 | 35191190 |
| 25 | 61883196 |
| 26 | 107179834 |
| 27 | 187216848 |
| 28 | 321395596 |
| 29 | 558468104 |
[0,2,8,24,64,156,358,786,1664,3434,6902,13656, 26464,50772,95754,179442,331294,609496,1106106, 2004852,3586874,6423028,11351274,20126538, 35191190,61883196,107179834,187216848,321395596, 558468104] |