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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 0 |
| 9 | 21 |
| 10 | 107 |
| 11 | 619 |
| 12 | 1300 |
| 13 | 6740 |
| 14 | 19812 |
| 15 | 61075 |
| 16 | 181036 |
| 17 | 577551 |
| 18 | 1626183 |
| 19 | 4904626 |
| 20 | 14071461 |
| 21 | 41336066 |
| 22 | 120630534 |
| 23 | 352200161 |
| 24 | 1023454347 |
| 25 | 2997105957 |
| 26 | 8761810505 |
| 27 | 25648786717 |
| 28 | 75161609591 |
| 29 | 220583137840 |
| 30 | 647825855933 |
[0,0,0,0,0,0,1,0,21,107,619,1300,6740,19812,61075, 181036,577551,1626183,4904626,14071461,41336066, 120630534,352200161,1023454347,2997105957, 8761810505,25648786717,75161609591,220583137840, 647825855933] |