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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 40 |
| 5 | 203 |
| 6 | 1222 |
| 7 | 8557 |
| 8 | 68460 |
| 9 | 616146 |
| 10 | 6161460 |
| 11 | 67776061 |
| 12 | 813312734 |
| 13 | 10573065543 |
| 14 | 148022917610 |
| 15 | 2220343764162 |
| 16 | 35525500226600 |
| 17 | 603933503852210 |
| 18 | 10870803069339780 |
| 19 | 206545258317455828 |
| 20 | 4130905166349116567 |
[1,3,10,40,203,1222,8557,68460,616146,6161460, 67776061,813312734,10573065543,148022917610, 2220343764162,35525500226600,603933503852210, 10870803069339780,206545258317455828, 4130905166349116567] |