Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_20 (week INTEGER, date VARCHAR, attendance VARCHAR)
### Question:
What is the sum of the weeks that games occured on october 21, 1974 and less than 50,623 fans attended?
### Answer:
SELECT SUM(week) FROM table_name_20 WHERE date = "october 21, 1974" AND attendance < 50 OFFSET 623