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_20538157_2 ( written_by VARCHAR, no_in_season VARCHAR )

### Question ###
Who were the writers of episode 20?

### Accurate SQL ###

SELECT written_by FROM table_20538157_2 WHERE no_in_season = 20