  Given 2-factors $R$ and $S$ of order $n$, let $r$ and $s$ be nonnegative
integers with $r+s=\lfloor \frac{n-1}{2}\rfloor$, the Hamilton-Waterloo problem
asks for a 2-factorization of $K_n$ if $n$ is odd, or of $K_n-I$ if $n$ is
even, in which $r$ of its 2-factors are isomorphic to $R$ and the other $s$
2-factors are isomorphic to $S$. In this paper, we solve the problem for the
case of triangle-factors and heptagon-factors for odd $n$ with 3 possible
exceptions when $n=21$.
