CREATE TABLE table_name_30 (featuring VARCHAR, doctor VARCHAR, series_sorted VARCHAR)

who is the featuring when the doctor is the 6th and the series sorted is 6y/ak?
SELECT featuring FROM table_name_30 WHERE doctor = "6th" AND series_sorted = "6y/ak"
SELECT "featuring" FROM "table_name_30" WHERE "6th" = "doctor" AND "6y/ak" = "series_sorted"