Which song was an inspiration to Douglas Adams writing "The Restaurant at the End of the Universe?"

The Restaurant at the End of the Universe, the second novel in the series, is dedicated to the 1980 Paul Simon soundtrack album, One-Trick Pony. Adams says he played it "incessantly" while writing the book
https://en.wikipedia.org/wiki/Douglas_Adams

The second book in Douglas Adams's Hitchhiker Trilogy, The Restaurant at the End of the Universe, was inspired by the song "Grand Hotel", from Procol Harum's album of the same name.

https://en.wikipedia.org/wiki/Procul_Harum

Paul Simon or Procul Harum? wikipedia does have it's problems.

My paperback edition of "Restaurant" published by Pan in 1983 contains among other dedications
"to the Paul Simon album "One Trick Pony" which I played incessantly while writing this book. Five years is far too long"

Inspiration and dedication are not the same thing.

The book was inspired by "Grand Hotel" and dedicated to "One Trick Pony".

"Adams also let it be known that while writing he would listen to music, and this would occasionally influence his work. On one occasion the title track from the Procol Harum album Grand Hotel was playing when...

"Suddenly in the middle of the song there was this huge orchestral climax that came out of nowhere and did not seem to be about anything. I kept wondering what was this huge thing happening in the background? And I eventually thought ... it sounds as if there ought to be some sort of floorshow going on. Something huge and extraordinary, like, well, like the end of the universe. And so that was where the idea for The Restaurant at the End of the Universe came from.

– Douglas Adams, Procol Harum at The Barbican""

https://en.wikipedia.org/wiki/Douglas_Adams