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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 13 |
| 6 | 46 |
| 7 | 160 |
| 8 | 658 |
| 9 | 2867 |
| 10 | 13481 |
| 11 | 68123 |
| 12 | 363995 |
| 13 | 2059994 |
| 14 | 12265480 |
| 15 | 76553192 |
| 16 | 499565710 |
| 17 | 3397751507 |
| 18 | 24030183367 |
| 19 | 176345076712 |
| 20 | 1340147071794 |
| 21 | 10528875578996 |
| 22 | 85382909823373 |
| 23 | 713673454720854 |
| 24 | 6140525989112831 |
| 25 | 54321576239313034 |
| 26 | 493542862587980827 |
[1,1,1,2,5,13,46,160,658,2867,13481,68123,363995, 2059994,12265480,76553192,499565710,3397751507, 24030183367,176345076712,1340147071794, 10528875578996,85382909823373,713673454720854, 6140525989112831,54321576239313034, 493542862587980827] |