MathDB
squares in a bw chessboard

Source: JBMO Shortlist 2007 C3

October 14, 2017
JBMOcombinatoricsChessboard

Problem Statement

The nonnegative integer nn and (2n+1)×(2n+1) (2n + 1) \times (2n + 1) chessboard with squares colored alternatively black and white are given. For every natural number mm with 1<m<2n+11 < m < 2n+1, an m×mm \times m square of the given chessboard that has more than half of its area colored in black, is called a BB-square. If the given chessboard is a BB-square, fi nd in terms of nn the total number of BB-squares of this chessboard.