CREATE TABLE table_29531 ("No. in series" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "U.S. viewers  ( millions ) " CLOB, "Original U.S. air date" CLOB, "Prod. code" FLOAT)

How many millions of US viewers watched the episode written by Jack Sanderson?
SELECT "U.S. viewers (millions)" FROM table_29531 WHERE "Written by" = 'Jack Sanderson'
SELECT "U.S. viewers (millions)" FROM "table_29531" WHERE "Written by" = 'Jack Sanderson'