Problem 43179. Red and green towers

Frankie has a large number of wooden cubes, painted in red and green. He is building little towers with his cubes, by stacking them on top of each other.

He got bored after a while, so he introduced a rule: two red cubes may not be touching (see image).

Given n (the maximum number of cubes in a tower), determine the number m of different towers that Frankie can build.

Example: for n = 2, he can make 5 towers, so m=5:

  1. [Red];
  2. [Green];
  3. [Red, Green];
  4. [Green, Red];
  5. [Green, Green].

You may assume that the input is an integer greater than zero.

Solution Stats

89.47% Correct | 10.53% Incorrect
Last Solution submitted on May 29, 2020

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