gistfile1.rb

FIB = [0, 1]

def fib(n, seed = nil)
  seed = FIB.take(n).each { |x| puts x } unless seed
  seed << (seed[-1] + seed[-2]).tap { |x| puts x; FIB << x } if seed.size == n

  while s = seed.size and s < n
    fib(s, seed)
  end

  seed[n]
end