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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 10 |
| 5 | 33 |
| 6 | 100 |
| 7 | 290 |
| 8 | 795 |
| 9 | 2098 |
| 10 | 5353 |
| 11 | 13270 |
| 12 | 32058 |
| 13 | 75681 |
| 14 | 174982 |
| 15 | 396969 |
| 16 | 885035 |
| 17 | 1941744 |
| 18 | 4197219 |
| 19 | 8947798 |
| 20 | 18829981 |
| 21 | 39148311 |
| 22 | 80467194 |
| 23 | 163624700 |
| 24 | 329349740 |
| 25 | 656560785 |
| 26 | 1296916079 |
| 27 | 2539570658 |
| 28 | 4931698805 |
| 29 | 9501297338 |
[1,0,0,2,10,33,100,290,795,2098,5353,13270,32058, 75681,174982,396969,885035,1941744,4197219, 8947798,18829981,39148311,80467194,163624700, 329349740,656560785,1296916079,2539570658, 4931698805,9501297338] |