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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 29 |
| 6 | 88 |
| 7 | 271 |
| 8 | 876 |
| 9 | 2880 |
| 10 | 9699 |
| 11 | 33106 |
| 12 | 114575 |
| 13 | 400547 |
| 14 | 1413333 |
| 15 | 5025026 |
| 16 | 17987892 |
| 17 | 64769123 |
| 18 | 234438337 |
| 19 | 852519108 |
| 20 | 3113091384 |
| 21 | 11410682109 |
| 22 | 41967420293 |
| 23 | 154832147286 |
| 24 | 572853387928 |
| 25 | 2124996514900 |
| 26 | 7901625442544 |
| 27 | 29446874224295 |
| 28 | 109965454516498 |
[0,1,2,4,11,29,88,271,876,2880,9699,33106,114575, 400547,1413333,5025026,17987892,64769123, 234438337,852519108,3113091384,11410682109, 41967420293,154832147286,572853387928, 2124996514900,7901625442544,29446874224295, 109965454516498] |