CREATE TABLE table_74249 ("\\u2116" FLOAT, "#" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Production code" CLOB, "U.S. viewers  ( millions ) " CLOB)

What is the series No when the season 4 # is 18?
SELECT MIN("\u2116") FROM table_74249 WHERE "#" = '18'
SELECT MIN("\u2116") FROM "table_74249" WHERE "#" = '18'