Did a film producer direct M1 and M2 , direct M3 , and direct M4 's prequel
SELECT count(*) WHERE {
?x0 a ns:film.producer .
?x0 ns:film.director.film ?x1 .
?x0 ns:film.director.film M1 .
?x0 ns:film.director.film M2 .
?x0 ns:film.director.film M3 .
?x1 ns:film.film.sequel M4
}