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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 6 | 66 |
| 7 | 112 |
| 8 | 456 |
| 9 | 765 |
| 10 | 15070 |
| 11 | 31856 |
| 12 | 150756 |
| 13 | 663962 |
| 14 | 1943046 |
| 15 | 44316105 |
| 16 | 127348864 |
| 17 | 661449549 |
| 18 | 3220447446 |
| 19 | 20913769072 |
| 20 | 68889553260 |
| 21 | 2403704171190 |
| 22 | 7894983374674 |
| 23 | 51012052828947 |
| 24 | 270186003789312 |
| 25 | 1836634462055350 |
| 26 | 13402212376611266 |
[0,1,0,3,4,5,66,112,456,765,15070,31856,150756, 663962,1943046,44316105,127348864,661449549, 3220447446,20913769072,68889553260,2403704171190, 7894983374674,51012052828947,270186003789312, 1836634462055350,13402212376611266] |