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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 16 |
| 6 | 52 |
| 7 | 170 |
| 8 | 556 |
| 9 | 1821 |
| 10 | 5973 |
| 11 | 19620 |
| 12 | 64536 |
| 13 | 212553 |
| 14 | 700903 |
| 15 | 2313864 |
| 16 | 7646670 |
| 17 | 25294673 |
| 18 | 83748689 |
| 19 | 277518319 |
| 20 | 920332567 |
| 21 | 3054319120 |
| 22 | 10143305864 |
| 23 | 33707066667 |
| 24 | 112078220233 |
| 25 | 372875904038 |
| 26 | 1241182355688 |
| 27 | 4133534991928 |
| 28 | 13772413826888 |
| 29 | 45908128269573 |
[1,1,5,16,52,170,556,1821,5973,19620,64536,212553, 700903,2313864,7646670,25294673,83748689, 277518319,920332567,3054319120,10143305864, 33707066667,112078220233,372875904038, 1241182355688,4133534991928,13772413826888, 45908128269573] |