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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 36 |
| 4 | 118 |
| 5 | 376 |
| 6 | 1148 |
| 7 | 3376 |
| 8 | 9654 |
| 9 | 26894 |
| 10 | 73192 |
| 11 | 195188 |
| 12 | 510948 |
| 13 | 1315048 |
| 14 | 3332720 |
| 15 | 8326448 |
| 16 | 20529526 |
| 17 | 49998884 |
| 18 | 120379574 |
| 19 | 286726340 |
| 20 | 676057144 |
| 21 | 1578880480 |
| 22 | 3654180236 |
| 23 | 8385122192 |
| 24 | 19085029540 |
| 25 | 43103203626 |
| 26 | 96630606968 |
| 27 | 215105226728 |
| 28 | 475608824400 |
[1,2,10,36,118,376,1148,3376,9654,26894,73192, 195188,510948,1315048,3332720,8326448,20529526, 49998884,120379574,286726340,676057144,1578880480, 3654180236,8385122192,19085029540,43103203626, 96630606968,215105226728,475608824400] |