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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 34 |
| 6 | 162 |
| 7 | 822 |
| 8 | 4365 |
| 9 | 23956 |
| 10 | 134814 |
| 11 | 773746 |
| 12 | 4511693 |
| 13 | 26652346 |
| 14 | 159170385 |
| 15 | 959412290 |
| 16 | 5829083420 |
| 17 | 35661048886 |
| 18 | 219491344362 |
| 19 | 1358204062536 |
| 20 | 8444658457530 |
| 21 | 52729475008690 |
| 22 | 330518562341537 |
| 23 | 2078987880103170 |
[1,0,1,2,8,34,162,822,4365,23956,134814,773746, 4511693,26652346,159170385,959412290,5829083420, 35661048886,219491344362,1358204062536, 8444658457530,52729475008690,330518562341537, 2078987880103170] |