Elementary Number Theory: Primes, Congruences, and Secrets
Another open source book posted on GitHub. Another book added to my mathematical to-read list. The picture, from Wikipedia: A Lehmer sieve, which is a primitive digital computer once used for finding primes and solving simple Diophantine equations.
Iain M. Banks: The Culture Series
I've just started reading Iain M. Banks, starting with Consider Phlebas, his first science fiction novel. Banks died a few weeks ago and upon reading of his death I was subsequently prompted to read up on his work. The Culture series stood out as my "cup-of-tea".