In Carl Sagan's 'Contact', "Ellie, acting upon a suggestion by the senders of the message, works on a program which computes the digits of π to record lengths and in different bases. Very, very far from the decimal point (1020) and in base 11, it finds that a special pattern does exist when the numbers stop varying randomly and start producing 1s and 0s in a very long string. The string's length is the product of 11 prime numbers. The 1s and 0s when organized as a square of specific dimensions form a rasterized circle."