CREATE TABLE table_25760 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

Who wrote the episode that had a production code of 3ajn20?
SELECT "Written by" FROM table_25760 WHERE "Production code" = '3AJN20'
SELECT "Written by" FROM "table_25760" WHERE "Production code" = '3AJN20'