Question 28
S6 (IND). Let $\mathbb N$ denote the set of all positive integers. Prove that there exists a unique function $f:\mathbb N\to\mathbb N$ satisfying
$$f(m+f(n))=n+f(m+95)$$
for all $m$ and $n$ in $\mathbb N$. What is the value of $\sum_{k=1}^{19}f(k)$?
$$f(m+f(n))=n+f(m+95)$$
for all $m$ and $n$ in $\mathbb N$. What is the value of $\sum_{k=1}^{19}f(k)$?