What TV show has the theme song welcome back?

The TV show with the theme song "Welcome Back" is "Welcome Back, Kotter." It premiered in 1975 and starred Gabe Kaplan as a teacher returning to his high school alma mater to teach a group of underachieving students known as the "Sweathogs." The song, performed by John Sebastian, became iconic and is closely associated with the show's nostalgic themes.