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_15211468_3 (episode_no VARCHAR, presenter VARCHAR)

### Question ###
What episode number is presented by Ben Okri ?

### Accurate SQL ###

SELECT episode_no FROM table_15211468_3 WHERE presenter = "Ben Okri"