The date of the first Broadway preview is sometimes incorrectly listed as January 6, 1971, and the number of Broadway previews is sometimes incorrectly listed as 13. Previews actually started on January 7, and there were 14.
Although January 7 was a Thursday, the production played both a matinee and an evening performance that day. The production was playing on a Monday through Saturday schedule. Because of the Thursday matinee that first week, five performances were played that week. A standard eight performances were played the second week. There was one last production on Monday, January 18. Hence, the total was 14.