Counting free subgroups of finite index (Q1325227)

Let \(G\) be a finitely generated (infinite) virtually free group and denote by \(m_ G\) the least common multiple of the orders of the finite subgroups in \(G\). The author continues the investigation of the function \(b_ G : N \to N\), where \(b_ G (\lambda)\) is the number of free subgroups of index \(\lambda m_ G\) in \(G\). An asymptotic expansion of the function \(b_ G(\lambda)\) is found. Also the author considers examples which demonstrate the precision of the expansions obtained.