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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 22 |
| 7 | 110 |
| 8 | 515 |
| 9 | 2272 |
| 10 | 9777 |
| 11 | 40752 |
| 12 | 166519 |
| 13 | 668134 |
| 14 | 2644988 |
| 15 | 10351321 |
| 16 | 40150556 |
| 17 | 154591610 |
| 18 | 591780559 |
| 19 | 2254880616 |
| 20 | 8561287942 |
| 21 | 32418230925 |
| 22 | 122522492807 |
| 23 | 462502319244 |
| 24 | 1744810912396 |
| 25 | 6581954720648 |
| 26 | 24839735669771 |
[1,4,22,110,515,2272,9777,40752,166519,668134, 2644988,10351321,40150556,154591610,591780559, 2254880616,8561287942,32418230925,122522492807, 462502319244,1744810912396,6581954720648, 24839735669771] |