user: Question: What is the series episode number of the episode with production code 303?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original airdate', 'Production code']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['27–28', '1–2', '"Vengeance of Vilgax"', 'Dan Riba and Butch Lukic', 'Dwayne McDuffie', 'September11,2009', '301–302']
SQL:

assistant: SELECT "No. in series" FROM "Table" WHERE "Production code" = '303';