And later, he wrote the theme song for "Welcome Back, Kotter." (Originally, he wrote only 1 verse for the show, for the 45 version added a 2nd verse and an instrumental break featuring harmonica).
He also came to ISU during my times there. Probably around '76-77. It was at C Y Stephens and he specifically mentioned that that song was probably the reason he was touring. I think it may have actually been free, but memories are faded.
I also saw The Who (minus Keith) and CSN at ISU during my time there.