CREATE TABLE table_4118 ("Series #" FLOAT, "Season #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT)

What is the production code for the episode that aired on October 15, 2004?
SELECT "Production code" FROM table_4118 WHERE "Original air date" = 'October 15, 2004'
SELECT "Production code" FROM "table_4118" WHERE "Original air date" = 'October 15, 2004'