If a prime number is the sum of two squares, then it’s not a Gaussian prime. So when you note that 13 = 4+9, and that 89 = 25+64, you’re observing that 13 and 89 are not Gaussian primes. It ...

A modest pencil drawing of the wreathed head of the god Silenus will go on public display for the first time in Derby this week. The drawing is the earliest known work by the city’s most famous ...