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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 17 |
| 3 | 71 |
| 4 | 300 |
| 5 | 1271 |
| 6 | 5383 |
| 7 | 22802 |
| 8 | 96591 |
| 9 | 409165 |
| 10 | 1733250 |
| 11 | 7342165 |
| 12 | 31101909 |
| 13 | 131749800 |
| 14 | 558101109 |
| 15 | 2364154235 |
| 16 | 10014718048 |
| 17 | 42423026427 |
| 18 | 179706823755 |
| 19 | 761250321446 |
| 20 | 3224708109539 |
| 21 | 13660082759601 |
| 22 | 57865039147942 |
[1,4,17,71,300,1271,5383,22802,96591,409165, 1733250,7342165,31101909,131749800,558101109, 2364154235,10014718048,42423026427,179706823755, 761250321446,3224708109539,13660082759601, 57865039147942] |