What days are vacant that were replaced by john brown?
CREATE TABLE table_16516 (
    "Team" text,
    "Outgoing manager" text,
    "Manner of departure" text,
    "Date of vacancy" text,
    "Replaced by" text,
    "Date of appointment" text
)
SELECT "Date of vacancy" FROM table_16516 WHERE "Replaced by" = 'John Brown'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What days are vacant that were replaced by john brown? ### Input: CREATE TABLE table_16516 (
    "Team" text,
    "Outgoing manager" text,
    "Manner of departure" text,
    "Date of vacancy" text,
    "Replaced by" text,
    "Date of appointment" text
) ### Response: SELECT "Date of vacancy" FROM table_16516 WHERE "Replaced by" = 'John Brown'