user: Question: Which episode number had a viewership of 0.56 million?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'U.S. viewers (million)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [47.0, 1.0, '"Happy Fucking Birthday"', 'Randall Einhorn', 'Clyde Phillips', 'April14,2013', '0.77']
SQL:

assistant: SELECT "No. in series" FROM "Table" WHERE "U.S. viewers (million)" = '0.56';