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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 75 |
| 6 | 264 |
| 7 | 914 |
| 8 | 3127 |
| 9 | 10621 |
| 10 | 35932 |
| 11 | 121324 |
| 12 | 409301 |
| 13 | 1380417 |
| 14 | 4655382 |
| 15 | 15700590 |
| 16 | 52954137 |
| 17 | 178609067 |
| 18 | 602449564 |
| 19 | 2032105066 |
| 20 | 6854506171 |
| 21 | 23121097405 |
| 22 | 77990499392 |
| 23 | 263072412420 |
| 24 | 887378656761 |
| 25 | 2993247393297 |
| 26 | 10096624106970 |
| 27 | 34057260581510 |
[1,2,6,21,75,264,914,3127,10621,35932,121324, 409301,1380417,4655382,15700590,52954137, 178609067,602449564,2032105066,6854506171, 23121097405,77990499392,263072412420,887378656761, 2993247393297,10096624106970,34057260581510] |