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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 50 |
| 6 | 195 |
| 7 | 721 |
| 8 | 2716 |
| 9 | 10116 |
| 10 | 37845 |
| 11 | 141295 |
| 12 | 528330 |
| 13 | 1975766 |
| 14 | 7395479 |
| 15 | 27698685 |
| 16 | 103821240 |
| 17 | 389410568 |
| 18 | 1461605481 |
| 19 | 5489516955 |
| 20 | 20630539910 |
| 21 | 77579118330 |
| 22 | 291893775019 |
| 23 | 1098848179561 |
| 24 | 4138773239892 |
| 25 | 15596070165900 |
| 26 | 58797332264125 |
| 27 | 221762856917511 |
| 28 | 836756771788098 |
[0,0,1,3,14,50,195,721,2716,10116,37845,141295, 528330,1975766,7395479,27698685,103821240, 389410568,1461605481,5489516955,20630539910, 77579118330,291893775019,1098848179561, 4138773239892,15596070165900,58797332264125, 221762856917511,836756771788098] |