MathDB
Combinatorics Question

Source:

August 11, 2019
combinatoricscountingdistinguishability

Problem Statement

We will say that a rearrangement of the letters of a word has no fixed letters if, when the rearrangement is placed directly below the word, no column has the same letter repeated. For instance HBRATAHBRATA is a rearragnement with no fixed letter of BHARATBHARAT. How many distinguishable rearrangements with no fixed letters does BHARATBHARAT have? (The two AAs are considered identical.)