What is the production number of "rain of terror"?
CREATE TABLE "table1_13740746_1" (
  "ep_no" real,
  "title" text,
  "director" text,
  "written_by" text,
  "original_air_date" text,
  "production_no" real
);
SELECT MIN("production_no") FROM "table1_13740746_1" WHERE "title"='\"Rain of Terror\"';