user: Question: Who were the writers for series number 20?
Columns: ['Series #', 'Title', 'Directed by', 'Written by', 'Musical guest and song', 'Original air date', 'Production code']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '"School Ties"', 'Arthur W. Forney', 'Natalie Chaidez', 'Teddy Pendergrass " Close the Door "', 'September 8, 1994', 70103.0]
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Series #" = 20.0;