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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 20 |
| 3 | 58 |
| 4 | 161 |
| 5 | 436 |
| 6 | 1165 |
| 7 | 3088 |
| 8 | 8146 |
| 9 | 21426 |
| 10 | 56255 |
| 11 | 147538 |
| 12 | 386681 |
| 13 | 1013026 |
| 14 | 2653240 |
| 15 | 6948058 |
| 16 | 18193141 |
| 17 | 47634936 |
| 18 | 124717445 |
| 19 | 326526748 |
| 20 | 854877926 |
| 21 | 2238131506 |
| 22 | 5859556195 |
| 23 | 15340601158 |
| 24 | 40162350961 |
| 25 | 105146619486 |
| 26 | 275277778940 |
[1,6,20,58,161,436,1165,3088,8146,21426,56255, 147538,386681,1013026,2653240,6948058,18193141, 47634936,124717445,326526748,854877926,2238131506, 5859556195,15340601158,40162350961,105146619486, 275277778940] |