gistfile1.rb

# 0: false
# 1: 0
# 2: true
# 3: 1
# 4: nil
# 5: 2
# ...
# 338: :"!"
# 378: :%
# 388: :&
# 428: :*
# 438: :+
# 458: :-
# 478: :/

(0..20_000).to_a.each do |id|
  begin
    object = ObjectSpace._id2ref(id)
    puts "#{id}: #{object.inspect}" unless object.is_a? Fixnum
  rescue RangeError
  end
end

# >> :"!".object_id
# => 338
# >> :"!".to_i
# => 33
# >> :%.object_id
# => 378
# >> :%.to_i
# => 37