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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 31 |
| 5 | 99 |
| 6 | 405 |
| 7 | 1419 |
| 8 | 5953 |
| 9 | 22065 |
| 10 | 96413 |
| 11 | 370294 |
| 12 | 1634168 |
| 13 | 6465684 |
| 14 | 28845552 |
| 15 | 116211498 |
| 16 | 525501390 |
| 17 | 2151401160 |
| 18 | 9780421638 |
| 19 | 40586651280 |
| 20 | 185562016495 |
| 21 | 777580903830 |
| 22 | 3577734848131 |
| 23 | 15126428257970 |
| 24 | 69843964271976 |
| 25 | 297606647531008 |
| 26 | 1378863798686027 |
| 27 | 5911859813254132 |
| 28 | 27491122663909053 |
[1,1,3,8,31,99,405,1419,5953,22065,96413,370294, 1634168,6465684,28845552,116211498,525501390, 2151401160,9780421638,40586651280,185562016495, 777580903830,3577734848131,15126428257970, 69843964271976,297606647531008,1378863798686027, 5911859813254132,27491122663909053] |