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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 2 |
| 6 | 9 |
| 7 | 29 |
| 8 | 108 |
| 9 | 399 |
| 10 | 1573 |
| 11 | 6249 |
| 12 | 25642 |
| 13 | 107751 |
| 14 | 466898 |
| 15 | 2071183 |
| 16 | 9429453 |
| 17 | 43889227 |
| 18 | 209111720 |
| 19 | 1017353435 |
| 20 | 5056450994 |
| 21 | 25627110560 |
| 22 | 132451351403 |
| 23 | 697165582228 |
| 24 | 3736595119730 |
| 25 | 20372395392794 |
| 26 | 112961465325799 |
| 27 | 636497947945382 |
| 28 | 3643481367551384 |
[1,2,9,29,108,399,1573,6249,25642,107751,466898, 2071183,9429453,43889227,209111720,1017353435, 5056450994,25627110560,132451351403,697165582228, 3736595119730,20372395392794,112961465325799, 636497947945382,3643481367551384] |