CREATE TABLE table_29584044_1 (original_air_date VARCHAR2, no_in_series VARCHAR2)

What is the original air date of the episode that was number 31 in the series?
SELECT original_air_date FROM table_29584044_1 WHERE no_in_series = 31
SELECT "original_air_date" FROM "table_29584044_1" WHERE "no_in_series" = 31