#! /usr/bin/env ruby
require 'bigdecimal'

N, K = gets.chop.split.map(&:to_i)

@sum = 0

(1..N).to_a.each do |i|
  now = i
  probability = Rational(1, N)
  while now < K do
    now *= 2
    probability *= Rational(1, 2)
  end
  @sum += probability
end

puts @sum.to_f