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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 21 |
| 6 | 92 |
| 7 | 469 |
| 8 | 2731 |
| 9 | 17985 |
| 10 | 131528 |
| 11 | 1059616 |
| 12 | 9319363 |
| 13 | 88833422 |
| 14 | 912393381 |
| 15 | 10043727089 |
| 16 | 117969438513 |
| 17 | 1472593659884 |
| 18 | 19467505081458 |
| 19 | 271704942613323 |
| 20 | 3992343851680466 |
| 21 | 61603531051030691 |
| 22 | 995949139457447931 |
| 23 | 16835191741257445589 |
| 24 | 296976010796327785530 |
| 25 | 5457427389713208932740 |
| 26 | 104308245862443706265341 |
| 27 | 2070461793105333579698992 |
| 28 | 42622090166454492404075635 |
[1,1,1,2,6,21,92,469,2731,17985,131528,1059616, 9319363,88833422,912393381,10043727089, 117969438513,1472593659884,19467505081458, 271704942613323,3992343851680466, 61603531051030691,995949139457447931, 16835191741257445589,296976010796327785530, 5457427389713208932740,104308245862443706265341, 2070461793105333579698992, 42622090166454492404075635] |