In the book by Arthur C Clarke Rendezvous with Rama the eponymous Ramans designed their interstellar craft with triple redundancy. Everything is built in threes

In the book by Arthur C Clarke Rendezvous with Rama the eponymous Ramans designed their interstellar craft with triple redundancy. Everything is built in threes - 3 airlocks, for example. The line I quoted is the very last line in the book, and is equal parts fascinating and chilling, a very apt end for a great book. I highly recommend you read it. If you are in the USA and have a library card, may I suggest the Libby app for Android and iPhone? Or of course buying it second hand from online bookstores is also an option: looks like a new paperback is about $4.55 at smile.amazon.com, used is about 1 to 3 dollars, Kindle version is $7.59. I don't recommend the other books in the series, they don't live up to the original, in my opinion. A similar book is Eon by Greg Bear, although less pure sci-fi exploration and more sci-fi adventure.