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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 4 |
| 7 | 12 |
| 8 | 66 |
| 9 | 433 |
| 10 | 3442 |
| 11 | 30404 |
| 12 | 294951 |
| 13 | 3093770 |
| 14 | 34846185 |
| 15 | 419020738 |
| 16 | 5355289843 |
| 17 | 72466668921 |
| 18 | 1034818990771 |
| 19 | 15548633703424 |
| 20 | 245182764121059 |
| 21 | 4047990858838185 |
| 22 | 69826392559499108 |
| 23 | 1256005988628521464 |
| 24 | 23517396850332614602 |
| 25 | 457623646061902648705 |
[0,0,0,1,1,4,12,66,433,3442,30404,294951,3093770, 34846185,419020738,5355289843,72466668921, 1034818990771,15548633703424,245182764121059, 4047990858838185,69826392559499108, 1256005988628521464,23517396850332614602, 457623646061902648705] |