<p>Comfortable, casual and loose fitting, our heavyweight dark color t-shirt will quickly become one of your favorites. Made from 6.0 oz, pre-shrunk 100% cotton, it wears well on anyone. We’ve double-needle stitched the bottom and sleeve hems for extra durability. Imported.</p>
Euler's product in relation to the zeta function, as Derbyshire refers to as the "golden key". Euler gave a thorough proof of this relation, which is an important aspect in the Riemann conjecture, relating to the distribution of primes.
One of the most beautiful equations in all of maths.