Asymptotics of Generating the Symmetric and Alternating Groups

Source abstract

The probability that a random pair of elements from the alternating group $A_{n}$ generates all of $A_{n}$ is shown to have an asymptotic expansion of the form $1-1/n-1/n^{2}-4/n^{3}-23/n^{4}-171/n^{5}-...$. This same asymptotic expansion is valid for the probability that a random pair of elements from the symmetric group $S_{n}$ generates either $A_{n}$ or $S_{n}$. Similar results hold for the case of $r$ generators ($r>2$).