Did a screenwriter executive produce M1 and M2 and executive produce M3 's sequel
SELECT count(*) WHERE {
?x0 a ns:film.writer .
?x0 ns:film.producer.films_executive_produced ?x1 .
?x0 ns:film.producer.films_executive_produced M1 .
?x0 ns:film.producer.films_executive_produced M2 .
?x1 ns:film.film.prequel M3
}