CREATE TABLE "table1_15823956_1" (
  "series" text,
  "episodes" real,
  "series_premiere" text,
  "series_finale" text,
  "region_1" text,
  "region_2" text,
  "region_4" text
);

Question: Which episode was N/A in region 1
SQL: SELECT "episodes" FROM "table1_15823956_1" WHERE "region_1"='N/A';

Question: When was series premiere on the pilot episode
SQL: SELECT "series_premiere" FROM "table1_15823956_1" WHERE "series"='Pilot';

Question: What is the region 1 date for series 4
SQL: SELECT "region_1" FROM "table1_15823956_1" WHERE "series"='4';

Question: How many episodes in the series that premieres 5 february 2012
SQL: SELECT "episodes" FROM "table1_15823956_1" WHERE "series_premiere"='5 February 2012';