CREATE TABLE table_28419 ("No." FLOAT, "#" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "U.S. viewers  ( million ) " TEXT, "Rank  ( week ) " TEXT, "Original air date" TEXT, "Production code" TEXT)

What was the production code of the episode ranked 28?
SELECT "Production code" FROM table_28419 WHERE "Rank (week)" = '28'
SELECT "Production code" FROM "table_28419" WHERE "Rank (week)" = '28'