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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 30 |
| 6 | 91 |
| 7 | 268 |
| 8 | 790 |
| 9 | 2308 |
| 10 | 6737 |
| 11 | 19609 |
| 12 | 57044 |
| 13 | 165796 |
| 14 | 481823 |
| 15 | 1400028 |
| 16 | 4068577 |
| 17 | 11825459 |
| 18 | 34380152 |
| 19 | 99981942 |
| 20 | 290854486 |
| 21 | 846397344 |
| 22 | 2463892294 |
| 23 | 7174933683 |
| 24 | 20900764811 |
| 25 | 60904875999 |
| 26 | 177535250815 |
| 27 | 517673673674 |
| 28 | 1509950058629 |
| 29 | 4405547856394 |
| 30 | 12857716906991 |
[0,0,1,3,10,30,91,268,790,2308,6737,19609,57044, 165796,481823,1400028,4068577,11825459,34380152, 99981942,290854486,846397344,2463892294, 7174933683,20900764811,60904875999,177535250815, 517673673674,1509950058629,4405547856394, 12857716906991] |