CREATE TABLE table_47444 ("Series Sorted" TEXT, "Title" TEXT, "Doctor" TEXT, "Featuring" TEXT, "Released" TEXT)

who is the featuring when the doctor is the 6th and the series sorted is 6y/ak?
SELECT "Featuring" FROM table_47444 WHERE "Doctor" = '6th' AND "Series Sorted" = '6y/ak'
SELECT "Featuring" FROM "table_47444" WHERE "Doctor" = '6th' AND "Series Sorted" = '6y/ak'