this sentence has

out.dot

digraph {
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
20->32
32->36
21->36
22->36
23->38
24->37
37->38
25->37
37->38
26->36
27->38
28->38
29->37
37->38
30->32
32->36
31->36
32->36
33->38
34->37
37->38
35->37
37->38
37->38
39->37
37->38
40->31
31->36
}

thissentencehas.rb

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

vertices = (20..40).to_a
$edges = []

class Integer
	def try
		length = "This sentence has #{self.to_words} letters".length
		if self != length
			$edges << [self, length]
			length.try
		end
	end
end

vertices.each(&:try)

dot = "digraph {\n#{vertices.join "\n"}\n"

for e1, e2 in $edges
	dot << "#{e1}->#{e2}\n"
end

File.write "out.dot", dot << "}\n"
`dot -Tpng out.dot -o out.png && xdg-open out.png`