MathCastle
Counting & ProbabilityChallengeRecursion, Catalan Numbers & Generating Functions

Recursion, Catalan Numbers & Generating Functions · Challenge problem

A 1×101\times10 strip is tiled with red 1×11\times1 squares, blue 1×11\times1 squares and 1×21\times2 dominoes, so that no two red squares are next to each other. How many tilings are there?