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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 40 |
| 5 | 185 |
| 6 | 726 |
| 7 | 3157 |
| 8 | 13112 |
| 9 | 56331 |
| 10 | 239230 |
| 11 | 1028522 |
| 12 | 4414224 |
| 13 | 19045039 |
| 14 | 82237442 |
| 15 | 356104140 |
| 16 | 1544056864 |
| 17 | 6707220443 |
| 18 | 29172892518 |
| 19 | 127058629852 |
| 20 | 554006070200 |
| 21 | 2418204764451 |
| 22 | 10565384173762 |
| 23 | 46202462762837 |
| 24 | 202207635999240 |
| 25 | 885642000534925 |
| 26 | 3881697614968706 |
[0,1,2,12,40,185,726,3157,13112,56331,239230, 1028522,4414224,19045039,82237442,356104140, 1544056864,6707220443,29172892518,127058629852, 554006070200,2418204764451,10565384173762, 46202462762837,202207635999240,885642000534925, 3881697614968706] |