CREATE TABLE table_24597 ("Season no." FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. Viewers  ( millions ) " TEXT)

What was the season number for production code E2110?
SELECT "Season no." FROM table_24597 WHERE "Production code" = 'E2110'
SELECT "Season no." FROM "table_24597" WHERE "Production code" = 'E2110'