user: Question: On what week were there 26243 in attendance on september 21, 1969?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 14, 1969', 'Kansas City Chiefs', 'L 27–9', 47988.0]
SQL:

assistant: SELECT "Week" FROM "Table" WHERE "Date" = 'september 21, 1969' AND "Attendance" < 26243.0;