Fibonacci algorithm with ruby

A series of numbers where each number is the sum of the two preceding ones, often used as an example for dynamic programming.

def fibonacci(value)
  fib = [0, 1]

  (2..(value)).each do |value_idx|
    fib[value_idx] = fib[value_idx - 1] + fib[value_idx - 2]
  end

  fib[value]
end

puts  fibonacci(7)
#=> 13