Belphegor Primes
October 31, 2014
Belphegor is one of the Seven Princes of Hell, charged with helping people make ingenious inventions and discoveries. Simon Singh gave the name Belphegor’s Prime to the number 1000000000000066600000000000001, which is the Number of the Beast, 666, from the Apocalypse, surrounded on each side by an unlucky 13 zeroes. Generally, Belphegor numbers Bn = (10^(n+3) + 666)*10^(n+1) + 1 have a 1, followed by n zeroes, followed by 666, followed by n zeroes, followed by 1. There are eight known Belphegor primes, with n ∈ {0, 13, 42, 506, 608, 2472, 2623, 28291} (A232448). You can read more about Belphegor primes at Cliff Pickover’s page.
Your task is to write a program that enumerates the Belphegor primes. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.
Programming Praxis 