Open xehoth opened 7 years ago
https://blog.xehoth.cc/BZOJ3453/
求$$\sum{i=0}^{n} \sum{j=1}^{a+i \times d} \sum_{l=1}^{j}l^k$$
https://blog.xehoth.cc/BZOJ3453/
求$$\sum{i=0}^{n} \sum{j=1}^{a+i \times d} \sum_{l=1}^{j}l^k$$