user: Question: How many million U.S. viewers watched the episode with the production code 3X6004?
Columns: ['No.', '#', 'Title', 'Directed by', 'Written by', 'U.S. air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [196.0, 1.0, '"Lazarus"', 'Kevin G. Fair', 'Don Whitehead & Holly Henderson', 'September24,2010', '3X6001', '2.98']
SQL:

assistant: SELECT "U.S. viewers (million)" FROM "Table" WHERE "Production code" = '3X6004';