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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 34 |
| 5 | 115 |
| 6 | 389 |
| 7 | 1316 |
| 8 | 4452 |
| 9 | 15061 |
| 10 | 50951 |
| 11 | 172366 |
| 12 | 583110 |
| 13 | 1972647 |
| 14 | 6673417 |
| 15 | 22576008 |
| 16 | 76374088 |
| 17 | 258371689 |
| 18 | 874065163 |
| 19 | 2956941266 |
| 20 | 10003260650 |
| 21 | 33840788379 |
| 22 | 114482567053 |
| 23 | 387291750188 |
| 24 | 1310198605996 |
| 25 | 4432370135229 |
| 26 | 14994600761871 |
| 27 | 50726371026838 |
[0,1,3,10,34,115,389,1316,4452,15061,50951,172366, 583110,1972647,6673417,22576008,76374088, 258371689,874065163,2956941266,10003260650, 33840788379,114482567053,387291750188, 1310198605996,4432370135229,14994600761871, 50726371026838] |