user: Question: Who wrote the episode that had a production code of 3AJN20?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [59.0, 1.0, '"1600 Candles"', 'Caleb Meurer', 'Rick Wiener & Kenny Schwartz', 'September28,2008', '3AJN20', '6.89']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Production code" = '3AJN20';