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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 54 |
| 5 | 218 |
| 6 | 911 |
| 7 | 3917 |
| 8 | 17235 |
| 9 | 77251 |
| 10 | 351498 |
| 11 | 1619362 |
| 12 | 7538944 |
| 13 | 35412306 |
| 14 | 167626988 |
| 15 | 798823025 |
| 16 | 3829325596 |
| 17 | 18453005188 |
| 18 | 89338777895 |
| 19 | 434343634600 |
| 20 | 2119679152092 |
| 21 | 10379998771157 |
| 22 | 50989711920778 |
| 23 | 251194614740028 |
| 24 | 1240735313801625 |
| 25 | 6143268099066535 |
[1,1,4,14,54,218,911,3917,17235,77251,351498, 1619362,7538944,35412306,167626988,798823025, 3829325596,18453005188,89338777895,434343634600, 2119679152092,10379998771157,50989711920778, 251194614740028,1240735313801625,6143268099066535] |