Returns the corresponding number from the fibonacci sequence

fibonacci_array.rb

class Integer
  def fibonicci
    a = 0
    b = 1
    if self == 1
      1
    elsif self == 0
      0
    elsif self > 1
      array1 = [0,1]
      self.times {|x|array1 << array1[x] + array1[x+1]}
      return array1[self]
    end
  end
end

puts "'#{12.fibonicci}' should equal '144'"