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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | 6 |
| 5 | 13 |
| 6 | 55 |
| 7 | 142 |
| 8 | 429 |
| 9 | 1495 |
| 10 | 4538 |
| 11 | 14894 |
| 12 | 50279 |
| 13 | 164189 |
| 14 | 554402 |
| 15 | 1883870 |
| 16 | 6371434 |
| 17 | 21854442 |
| 18 | 75183191 |
| 19 | 259137380 |
| 20 | 899092908 |
| 21 | 3127293679 |
| 22 | 10907931688 |
| 23 | 38188033950 |
| 24 | 133998312862 |
| 25 | 471339759941 |
| 26 | 1662075700667 |
| 27 | 5872497411731 |
| 28 | 20790187564837 |
| 29 | 73741279736768 |
[1,1,0,3,6,13,55,142,429,1495,4538,14894,50279, 164189,554402,1883870,6371434,21854442,75183191, 259137380,899092908,3127293679,10907931688, 38188033950,133998312862,471339759941, 1662075700667,5872497411731,20790187564837, 73741279736768] |