gistfile1.rb

def Archimedean_spiral n
  if n == 0
    return [ [ '#' ] ]
  else
    inner  = Archimedean_spiral(n - 1)
    length = inner.size 
    ret = []
    ret << ([ '#', '#' ] + ([ '#' ] * length) + [ '#', '#' ] )
    ret << ([ '#', ' ' ] + ([ ' ' ] * length) + [ ' ', ' ' ] )
    inner.each do |x|
      line = [ '#', ' ' ] + x + [ '#', ' ' ]
      ret << line
    end
    ret << ([ '#', ' ' ] + ([ ' ' ] * length) + [ '#', ' ' ] )
    ret << ([ '#', '#' ] + ([ '#' ] * length) + [ '#', ' ' ] )
    return ret
  end
end

n      = ARGV.first.to_i
spiral = Archimedean_spiral(n)
size   = spiral.size
spiral.each_with_index do |line1, i|
  line2 = spiral[size - i - 1]
  string = (line1 + [ '#' ] + line2.reverse).join('')
  puts string
end