CREATE TABLE table_21745 ("No. in series" CLOB, "No. in season" CLOB, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Production code" CLOB, "U.S. viewers  ( millions ) " CLOB)

How many viewers did the episode written by Warren Lieberstein & Halsted Sullivan have?
SELECT "U.S. viewers (millions)" FROM table_21745 WHERE "Written by" = 'Warren Lieberstein & Halsted Sullivan'
SELECT "U.S. viewers (millions)" FROM "table_21745" WHERE "Written by" = 'Warren Lieberstein & Halsted Sullivan'