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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 203 |
| 7 | 877 |
| 8 | 4140 |
| 9 | 21147 |
| 10 | 94828 |
| 11 | 389946 |
| 12 | 1527058 |
| 13 | 5846917 |
| 14 | 22257299 |
| 15 | 85116719 |
| 16 | 329147169 |
| 17 | 1292371138 |
| 18 | 5165744159 |
| 19 | 20781403539 |
| 20 | 83617668276 |
| 21 | 335483033770 |
| 22 | 1340729704086 |
| 23 | 5338181115652 |
| 24 | 21193583922048 |
| 25 | 84001778063348 |
| 26 | 332811761809618 |
[1,1,2,5,15,52,203,877,4140,21147,94828,389946, 1527058,5846917,22257299,85116719,329147169, 1292371138,5165744159,20781403539,83617668276, 335483033770,1340729704086,5338181115652, 21193583922048,84001778063348,332811761809618] |