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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 33 |
| 6 | 108 |
| 7 | 360 |
| 8 | 1259 |
| 9 | 4495 |
| 10 | 16726 |
| 11 | 63085 |
| 12 | 243465 |
| 13 | 956363 |
| 14 | 3809943 |
| 15 | 15373894 |
| 16 | 62802682 |
| 17 | 259047003 |
| 18 | 1078374062 |
| 19 | 4527106194 |
| 20 | 19143470222 |
| 21 | 81500734973 |
| 22 | 349136767609 |
| 23 | 1504001293329 |
| 24 | 6512451517597 |
| 25 | 28334377206645 |
| 26 | 123816571698718 |
| 27 | 543263369796293 |
| 28 | 2392666109152600 |
| 29 | 10574852319611663 |
[1,1,2,4,12,33,108,360,1259,4495,16726,63085, 243465,956363,3809943,15373894,62802682,259047003, 1078374062,4527106194,19143470222,81500734973, 349136767609,1504001293329,6512451517597, 28334377206645,123816571698718,543263369796293, 2392666109152600,10574852319611663] |