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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 11 |
| 3 | 0 |
| 4 | 20 |
| 5 | 88 |
| 6 | 242 |
| 7 | 627 |
| 8 | 2604 |
| 9 | 8137 |
| 10 | 28727 |
| 11 | 101137 |
| 12 | 350450 |
| 13 | 1221711 |
| 14 | 4290711 |
| 15 | 14968081 |
| 16 | 52427734 |
| 17 | 183691236 |
| 18 | 643194452 |
| 19 | 2252416158 |
| 20 | 7891461835 |
| 21 | 27639419217 |
| 22 | 96818359023 |
| 23 | 339160988868 |
| 24 | 1188063187221 |
| 25 | 4161765906348 |
| 26 | 14578893452507 |
[0,11,0,20,88,242,627,2604,8137,28727,101137, 350450,1221711,4290711,14968081,52427734, 183691236,643194452,2252416158,7891461835, 27639419217,96818359023,339160988868, 1188063187221,4161765906348,14578893452507] |