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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 12 |
| 6 | 28 |
| 7 | 69 |
| 8 | 193 |
| 9 | 614 |
| 10 | 2103 |
| 11 | 7359 |
| 12 | 25660 |
| 13 | 88914 |
| 14 | 309502 |
| 15 | 1102146 |
| 16 | 4092840 |
| 17 | 16046224 |
| 18 | 66410789 |
| 19 | 286905421 |
| 20 | 1273646720 |
| 21 | 5729762139 |
| 22 | 25881820352 |
| 23 | 116872997038 |
| 24 | 527375160184 |
| 25 | 2384407416357 |
| 26 | 10856086444051 |
| 27 | 50097994816979 |
| 28 | 235937202788389 |
[1,1,1,2,5,12,28,69,193,614,2103,7359,25660,88914, 309502,1102146,4092840,16046224,66410789, 286905421,1273646720,5729762139,25881820352, 116872997038,527375160184,2384407416357, 10856086444051,50097994816979,235937202788389] |