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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 27 |
| 6 | 79 |
| 7 | 240 |
| 8 | 750 |
| 9 | 2387 |
| 10 | 7711 |
| 11 | 25214 |
| 12 | 83315 |
| 13 | 277799 |
| 14 | 933596 |
| 15 | 3159187 |
| 16 | 10755190 |
| 17 | 36811479 |
| 18 | 126594819 |
| 19 | 437220744 |
| 20 | 1515844359 |
| 21 | 5273760446 |
| 22 | 18406122609 |
| 23 | 64426136558 |
| 24 | 226108087891 |
| 25 | 795486834627 |
| 26 | 2804993559426 |
[1,1,2,4,10,27,79,240,750,2387,7711,25214,83315, 277799,933596,3159187,10755190,36811479,126594819, 437220744,1515844359,5273760446,18406122609, 64426136558,226108087891,795486834627, 2804993559426] |