CREATE TABLE table_30278 ("Series no." FLOAT, "Season no." FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT, "U.S. viewers  ( millions ) " TEXT)

What season number was assigned to the episode identified with the production code 401?
SELECT "Season no." FROM table_30278 WHERE "Production code" = '401'
SELECT "Season no." FROM "table_30278" WHERE "Production code" = '401'