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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 33 |
| 6 | 152 |
| 7 | 663 |
| 8 | 2778 |
| 9 | 11413 |
| 10 | 46332 |
| 11 | 186867 |
| 12 | 750878 |
| 13 | 3011025 |
| 14 | 12060480 |
| 15 | 48277423 |
| 16 | 193186146 |
| 17 | 772908429 |
| 18 | 3091983236 |
| 19 | 12368675691 |
| 20 | 49476275622 |
| 21 | 197908422985 |
| 22 | 791640682440 |
| 23 | 3166577409831 |
| 24 | 12666340397546 |
| 25 | 50665425902853 |
| 26 | 202661837829132 |
| 27 | 810647630936803 |
[0,0,0,1,6,33,152,663,2778,11413,46332,186867, 750878,3011025,12060480,48277423,193186146, 772908429,3091983236,12368675691,49476275622, 197908422985,791640682440,3166577409831, 12666340397546,50665425902853,202661837829132, 810647630936803] |