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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 20 |
| 5 | 212 |
| 6 | 464 |
| 7 | 4361 |
| 8 | 17812 |
| 9 | 60532 |
| 10 | 123088 |
| 11 | 4117252 |
| 12 | 29724752 |
| 13 | 84585040 |
| 14 | 430795584 |
| 15 | 8219554697 |
| 16 | 47479991380 |
| 17 | 214977407060 |
| 18 | 898098431312 |
| 19 | 16268050731620 |
| 20 | 98128441675472 |
| 21 | 417822285118032 |
| 22 | 1654860158000960 |
| 23 | 35730391312348996 |
| 24 | 243329575991962320 |
[1,1,4,17,20,212,464,4361,17812,60532,123088, 4117252,29724752,84585040,430795584,8219554697, 47479991380,214977407060,898098431312, 16268050731620,98128441675472,417822285118032, 1654860158000960,35730391312348996, 243329575991962320] |