www.mikescher.com/www/statics/euler/Euler_Problem-027_explanation.md

If you looked at the previous problems you probably know what comes now ... (Sieve of Eratosthenes)[https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes].
To lower the amount of A-B combinations we have to check here are 2 rules I found out:

• B must be a (positive) prime, otherwise n=0 wouldn't yield a prime number
• When B is a prime A must be uneven. Otherwise for n=0 the resulting number would be even and so not a prime.