Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_29531 ( "No. in series" real, "Title" text, "Directed by" text, "Written by" text, "U.S. viewers (millions)" text, "Original U.S. air date" text, "Prod. code" real )

### Question ###
How many millions of US viewers watched the episode written by Jack Sanderson?

### Accurate SQL ###

SELECT "U.S. viewers (millions)" FROM table_29531 WHERE "Written by" = 'Jack Sanderson'