Alcatraz, the San Francisco Bay island notorious for its past as a federal penitentiary, has had a long history of conflict, including its use as a Civil War defense fort and as the site of the 1969 All Tribes American Indian occupation and protest that led to a new chapter in federal policy concerning Native Americans. Now part of the National Park system, “The Rock” is currently playing host to Shortening: Making Irrational Rational, an installation presented jointly by the National Park Service and artist-mathematician Nelson Saiers, Ph.D. New York-based Saiers creates art that explores the mysteries of the world through numbers. In his new installation, he addresses the relationship of numbers — including Pi — to prison sentences, often referred to by inmates as “football numbers.” Pi’s first 200 digits will be presented on football jerseys, including the number 85 displayed on a Chicago Bears jersey, which once served as Al Capone’s prison number. Access the island via Alcatraz Cruises (exhibition entry included in ticket price). Boats depart from San Francisco’s Pier 33.