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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 1 |
| 4 | 8 |
| 5 | 10 |
| 6 | 39 |
| 7 | 70 |
| 8 | 208 |
| 9 | 439 |
| 10 | 1162 |
| 11 | 2640 |
| 12 | 6641 |
| 13 | 15600 |
| 14 | 38362 |
| 15 | 91481 |
| 16 | 222688 |
| 17 | 534650 |
| 18 | 1295559 |
| 19 | 3119990 |
| 20 | 7544888 |
| 21 | 18194639 |
| 22 | 43958642 |
| 23 | 106072320 |
| 24 | 256167361 |
| 25 | 618303360 |
| 26 | 1492941842 |
| 27 | 3603915601 |
| 28 | 8701212248 |
| 29 | 21005629450 |
[1,0,2,1,8,10,39,70,208,439,1162,2640,6641,15600, 38362,91481,222688,534650,1295559,3119990,7544888, 18194639,43958642,106072320,256167361,618303360, 1492941842,3603915601,8701212248,21005629450] |