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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 112 |
| 7 | 1754 |
| 8 | 13074 |
| 9 | 63400 |
| 10 | 234014 |
| 11 | 712248 |
| 12 | 1882132 |
| 13 | 4457246 |
| 14 | 9679760 |
| 15 | 19584514 |
| 16 | 37367934 |
| 17 | 67849336 |
| 18 | 118085614 |
| 19 | 198107620 |
| 20 | 321870956 |
| 21 | 508359070 |
| 22 | 782972820 |
| 23 | 1179105738 |
| 24 | 1740089734 |
| 25 | 2521359260 |
| 26 | 3593085246 |
| 27 | 5043058972 |
[0,0,0,0,2,112,1754,13074,63400,234014,712248, 1882132,4457246,9679760,19584514,37367934, 67849336,118085614,198107620,321870956,508359070, 782972820,1179105738,1740089734,2521359260, 3593085246,5043058972] |