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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 20 |
| 5 | 52 |
| 6 | 180 |
| 7 | 531 |
| 8 | 1935 |
| 9 | 6087 |
| 10 | 23263 |
| 11 | 76284 |
| 12 | 302460 |
| 13 | 1024293 |
| 14 | 4164341 |
| 15 | 14491325 |
| 16 | 59869889 |
| 17 | 213175734 |
| 18 | 890626586 |
| 19 | 3231206448 |
| 20 | 13626322744 |
| 21 | 50188107221 |
| 22 | 213489198731 |
| 23 | 796147909708 |
| 24 | 3413510811070 |
| 25 | 12866323062939 |
| 26 | 55541100524599 |
| 27 | 211337027327417 |
| 28 | 917464966807871 |
| 29 | 3520595766869871 |
[1,1,3,6,20,52,180,531,1935,6087,23263,76284, 302460,1024293,4164341,14491325,59869889, 213175734,890626586,3231206448,13626322744, 50188107221,213489198731,796147909708, 3413510811070,12866323062939,55541100524599, 211337027327417,917464966807871,3520595766869871] |