\[B_{n}=\frac{1}{n+1}\sum_{k=1}^{n}\sum_{j=1}^{k}(-1)^{j}j^{n}{\genfrac{(}{)}{0.%
0pt}{}{n+1}{k-j}}\Bigg/{\genfrac{(}{)}{0.0pt}{}{n}{k}},\]