Representations of symmetric groups with non-trivial determinant

Abstract

We give a closed formula for the number of partitions A of n such that the corresponding irreducible representation V-lambda of S-n has non-trivial determinant. We determine how many of these partitions are self-conjugate and how many are hooks. This is achieved by characterizing the 2-core towers of such partitions. We also obtain a formula for the number of partitions of n such that the associated permutation representation of S-n has non-trivial determinant.