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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 59 |
| 6 | 210 |
| 7 | 771 |
| 8 | 2934 |
| 9 | 11472 |
| 10 | 45768 |
| 11 | 185861 |
| 12 | 766004 |
| 13 | 3196617 |
| 14 | 13484009 |
| 15 | 57423388 |
| 16 | 246560056 |
| 17 | 1066400837 |
| 18 | 4642659695 |
| 19 | 20329547786 |
| 20 | 89487624762 |
| 21 | 395791623498 |
| 22 | 1758066178058 |
| 23 | 7839884115870 |
| 24 | 35087407624114 |
| 25 | 157552832011704 |
| 26 | 709617265586454 |
| 27 | 3205147601026502 |
| 28 | 14514588343290364 |
[1,1,2,6,18,59,210,771,2934,11472,45768,185861, 766004,3196617,13484009,57423388,246560056, 1066400837,4642659695,20329547786,89487624762, 395791623498,1758066178058,7839884115870, 35087407624114,157552832011704,709617265586454, 3205147601026502,14514588343290364] |