(解決済)なんですか、これは？

$W\in \mathbb{R}, W>0, n\in \mathbb{N}, n>1$:

$$ \begin{eqnarray} \overline{W_1} &=& \frac{1}{W} \int_0^W w_1 dw_1 \\ \overline{W_2} &=& \frac{1}{W} \int_0^W \frac{1}{W-w_1} \int_0^{W-w_1} w_2 dw_2 dw_1 \\ \overline{W_3} &=& \frac{1}{W} \int_0^W \frac{1}{W-w_1} \int_0^{W-w_1} \frac{1}{W-w_1-w_2} \int_0^{W-w_1-w_2} w_3 dw_3 dw_2 dw_1 \\ \overline{W_4} &=& \frac{1}{W} \int_0^W \frac{1}{W-w_1} \int_0^{W-w_1} \frac{1}{W-w_1-w_2} \int_0^{W-w_1-w_2} \frac{1}{W-w_1-w_2-w_3} \int_0^{W-w_1-w_2-w_3} w_4 dw_4 dw_3 dw_2 dw_1 \\ \\ \overline{W_n} &=& \frac{1}{W} \int_0^W \frac{1}{W-w_1} \int_0^{W-w_1} \frac{1}{W-w_1-w_2} \int_0^{W-w_1-w_2} \cdots w_n dw_n \cdots dw_3 dw_2 dw_1 \\ \end{eqnarray} $$