Plus Magazine: "Mathematical Mysteries: Twin Primes"
Read this page. Take note of the definition of Brun's constant. Also note that this is related to the Intel's famous $475 million recall of Pentium chips. Please also feel free to click on the link to "Enumeration to 1e14 of the twin primes and Brun's constant" link at the end of the page to read associated content.
Click http://web.archive.org/web/20150423205612/https://plus.maths.org/content/mathematical-mysteries-twin-primes link to open resource.