Enumerating p-Groups

We present a new algorithm which uses a cohomological approach to determine the groups of order p n , where p is a prime. We develop two methods to enumerate p -groups using the Cauchy-Frobenius Lemma. As an application we show that there are 10 494213 groups of order 2 9 . 1991 Mathematics subject classification (Amer. Math. Soc.) : primary 20D15.