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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 42 |
| 5 | 162 |
| 6 | 730 |
| 7 | 3082 |
| 8 | 14290 |
| 9 | 63336 |
| 10 | 298514 |
| 11 | 1361600 |
| 12 | 6486758 |
| 13 | 30142468 |
| 14 | 144686738 |
| 15 | 681021198 |
| 16 | 3287160352 |
| 17 | 15617444040 |
| 18 | 75703276070 |
| 19 | 362216229252 |
| 20 | 1761679987258 |
| 21 | 8475504487054 |
| 22 | 41333249569972 |
| 23 | 199728941712302 |
| 24 | 976209612966736 |
| 25 | 4734057461781154 |
| 26 | 23181770959944304 |
| 27 | 112750725767858324 |
[1,1,3,10,42,162,730,3082,14290,63336,298514, 1361600,6486758,30142468,144686738,681021198, 3287160352,15617444040,75703276070,362216229252, 1761679987258,8475504487054,41333249569972, 199728941712302,976209612966736,4734057461781154, 23181770959944304,112750725767858324] |