CREATE TABLE "table1_15584067_4" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_million" text
);

Question: Name who wrote number 47
SQL: SELECT "written_by" FROM "table1_15584067_4" WHERE "no_in_series"=47;