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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 34 |
| 4 | 223 |
| 5 | 997 |
| 6 | 3402 |
| 7 | 9141 |
| 8 | 21665 |
| 9 | 46390 |
| 10 | 90874 |
| 11 | 167539 |
| 12 | 293443 |
| 13 | 487082 |
| 14 | 781537 |
| 15 | 1209469 |
| 16 | 1816528 |
| 17 | 2661113 |
| 18 | 3822203 |
| 19 | 5369662 |
| 20 | 7420495 |
| 21 | 10086360 |
| 22 | 13494376 |
[0,0,1,34,223,997,3402,9141,21665,46390,90874, 167539,293443,487082,781537,1209469,1816528, 2661113,3822203,5369662,7420495,10086360,13494376] |