# Problem 377: Sum of digits, experience 13
There are 16 positive integers that do not have a zero in their digits
and that have a digital sum equal to 5, namely: 5, 14, 23, 32, 41, 113,
122, 131, 212, 221, 311, 1112, 1121, 1211, 2111 and 11111. Their sum is
17891. Let f(n) be the sum of all positive integers that do not have a
zero in their digits and have a digital sum equal to n. Find
\$\\displaystyle \\sum\_{i=1}\^{17} f(13\^i)\$. Give the last 9 digits
as your answer.