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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 20 |
| 5 | 57 |
| 6 | 191 |
| 7 | 647 |
| 8 | 2204 |
| 9 | 7992 |
| 10 | 28194 |
| 11 | 104874 |
| 12 | 384720 |
| 13 | 1449306 |
| 14 | 5483215 |
| 15 | 20898490 |
| 16 | 80658514 |
| 17 | 311364894 |
| 18 | 1216690972 |
| 19 | 4756274956 |
| 20 | 18748495518 |
| 21 | 74099975703 |
| 22 | 294247939801 |
| 23 | 1173264704275 |
| 24 | 4690663672229 |
| 25 | 18833731765177 |
| 26 | 75769138632263 |
| 27 | 305949783943704 |
| 28 | 1237810577381054 |
| 29 | 5022401265853285 |
[1,1,3,6,20,57,191,647,2204,7992,28194,104874, 384720,1449306,5483215,20898490,80658514, 311364894,1216690972,4756274956,18748495518, 74099975703,294247939801,1173264704275, 4690663672229,18833731765177,75769138632263, 305949783943704,1237810577381054,5022401265853285] |