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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 10 |
| 5 | 21 |
| 6 | 81 |
| 7 | 224 |
| 8 | 803 |
| 9 | 2561 |
| 10 | 9050 |
| 11 | 30870 |
| 12 | 110319 |
| 13 | 390692 |
| 14 | 1416287 |
| 15 | 5140142 |
| 16 | 18897316 |
| 17 | 69766341 |
| 18 | 259721708 |
| 19 | 971424259 |
| 20 | 3655211118 |
| 21 | 13814548450 |
| 22 | 52455943266 |
| 23 | 199966174108 |
| 24 | 765230937806 |
| 25 | 2938440326656 |
| 26 | 11320368884041 |
| 27 | 43742501535980 |
| 28 | 169501362940771 |
| 29 | 658540291021676 |
| 30 | 2564869428603860 |
[1,0,2,2,10,21,81,224,803,2561,9050,30870,110319, 390692,1416287,5140142,18897316,69766341, 259721708,971424259,3655211118,13814548450, 52455943266,199966174108,765230937806, 2938440326656,11320368884041,43742501535980, 169501362940771,658540291021676,2564869428603860] |