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