The main result of this paper is the following: Let A be a self-injective Nakayama K-algebra, which is basic and connected. Suppose that A is a right Ae-module of τAe-period 1. (1) If A is an algebra whose Jacobson radical square is zero, then [Formula: see text]. (2) If A is an algebra whose Jacobson radical square is not zero, then [Formula: see text] for some positive integer n.