jmc

We want to sum the arithmetic series $11+13+\cdots +39$, which has common difference 2. Suppose the series has $n$ terms. 39 is the $n$th term, so $39=11+(n-1)\cdot 2$. Solving, we get $n=15$.The sum of an arithmetic series is equal to the average of the first and last term, multiplied by the number of terms, so the sum is $(11+39)/2\cdot 15=\boxed{375}$.