There are also 145 independent PEN Centers in 104 countries around the world . Each of these centers are open to qualified writers , journalists , translators , historians and others actively engaged in any branch of literature . International PEN is headquartered in London and composed of 145 autonomous PEN Centres in 104 countries around the world , each of which are open to qualified writers , journalists , translators , historians and others actively engaged in any branch of literature , regardless of nationality , race , color or religion .