CREATE TABLE table_name_20 (week NUMBER, date VARCHAR2, attendance VARCHAR2)

What is the sum of the weeks that games occured on october 21, 1974 and less than 50,623 fans attended?
SELECT SUM(week) FROM table_name_20 WHERE date = "october 21, 1974" AND attendance < 50 OFFSET 623
SELECT SUM("week") FROM "table_name_20" WHERE "attendance" < 50 AND "date" = "october 21, 1974" OFFSET 623 ROWS