user: Question: How many episodes had production number 2x13?
Columns: ['Series #', 'Season #', 'Episode Title', 'Original airdate', 'Prod. No.']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [21.0, 1.0, '"Mow Money / Love Stinks!"', 'April30,2011', '2x01']
SQL:

assistant: SELECT COUNT("Season #") FROM "Table" WHERE "Prod. No." = '2x13';