CREATE TABLE table_20312 ("Series" TEXT, "Episodes" FLOAT, "Series premiere" TEXT, "Series finale" TEXT, "Region 1" TEXT, "Region 2" TEXT, "Region 4" TEXT)

Which episode was N/A in region 1
SELECT "Episodes" FROM table_20312 WHERE "Region 1" = 'N/A'
SELECT "Episodes" FROM "table_20312" WHERE "Region 1" = 'N/A'