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| n | a(n) |
|---|---|
| 3 | 6 |
| 4 | 0 |
| 5 | 0 |
| 6 | 21 |
| 7 | 60 |
| 8 | 90 |
| 9 | 182 |
| 10 | 378 |
| 11 | 861 |
| 12 | 1737 |
| 13 | 3458 |
| 14 | 6717 |
| 15 | 13377 |
| 16 | 25877 |
| 17 | 49949 |
| 18 | 95085 |
| 19 | 180254 |
| 20 | 338003 |
| 21 | 631124 |
| 22 | 1168226 |
| 23 | 2151409 |
| 24 | 3934674 |
| 25 | 7159108 |
| 26 | 12948649 |
| 27 | 23307439 |
[6,0,0,21,60,90,182,378,861,1737,3458,6717,13377, 25877,49949,95085,180254,338003,631124,1168226, 2151409,3934674,7159108,12948649,23307439] |