dice_num, point = gets.chomp.split(' ').map(&:to_i)

prob = 0.0

(1..dice_num).each do |dice_roll|
  coin_roll_prob = (1.0/dice_num.to_f).to_f
  coin_roll_num = 0
  loop do
    if dice_roll >= point then
      prob = prob + coin_roll_prob
      break
    end
    dice_roll      = dice_roll * 2
    coin_roll_prob = (coin_roll_prob * (1.0/2.0).to_f).to_f
  end
end

print prob