What series number had an original airdate of March 1, 1991?
CREATE TABLE "table1_2409041_3" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real
);
SELECT MIN("no_in_series") FROM "table1_2409041_3" WHERE "original_air_date"='March 1, 1991';