CREATE TABLE table_17391 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT)

What's the season number of the episode titled 'Houseboat'?
SELECT "No. in season" FROM table_17391 WHERE "Title" = 'Houseboat'
SELECT "No. in season" FROM "table_17391" WHERE "Title" = 'Houseboat'