user: Question: What is the attendance in a week earlier than 4, and result is W 31-20?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 12, 1982', 'Los Angeles Raiders', 'L 23-17', 59748.0]
SQL:

assistant: SELECT "Attendance" FROM "Table" WHERE "Week" < 4.0 AND "Result" = 'W 31-20';