Peg Jumping for Fun and Profit
  We consider the problem of determining the minimum number of moves needed to solve a certain one-dimensional peg puzzle. Let N be a positive integer. The puzzle apparatus consists of a block with a single row of 2N+1 equally spaced holes which, apart from the central hole, are occupied by an equal number N of red and blue pegs. The object of the puzzle is to exchange the colors of the pegs by a succession of allowable moves. Allowable moves are of two types: a peg can be shifted from the hole it occupies into the empty hole adjacent to it, or a peg can jump over an adjacent peg into the empty hole. We exhibit a sequence of N^2+2N moves that solves the puzzle, and prove that no solution can employ fewer moves. 
David M. Bradley and Hugh Thomas