Orders for which there exist exactly six or seven groups

Abstract

Much progress has been made on the problem of calculating $g(n)$ for various classes of integers $n$, where $g$ is the group-counting function. We approach the inverse problem of solving the equations $g(n) = 6$ and $g(n) = 7$ in $n$. The determination of $n$ for which $g(n) = k$ has been carried out by G. A. Miller for $1 \le k \le 5$.