CREATE TABLE table_name_15 (format VARCHAR(255), label VARCHAR(255), catalog VARCHAR(255), date VARCHAR(255))
What is the format for the album under the label, luaka bop, that had a catalog number of 3645 and dated after 1981?
    
SQL: SELECT format FROM table_name_15 WHERE catalog = "3645" AND date > 1981 AND label = "luaka bop"