Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_29154676_1 (season_no INTEGER, us_viewers__millions_ VARCHAR)

### Question ###
What is the last episode in the season that had 3.91 million viewers in the US?

### Accurate SQL ###

SELECT MIN(season_no) FROM table_29154676_1 WHERE us_viewers__millions_ = "3.91"