A strong prime is precisely one for which the prime gap preceding it is strictly larger than the one following it. There are arbitrarily large prime gaps (for example none of the n numbers following n! are prime, since n!+m divides by m whenever m≤n). But it has recently been proven that there are infinitely many prime gaps with length less than or equal to 246. So given any strong prime we can find a prime gap after it which is longer than 246, and then a prime gap after that whose length is less than or equal to 246. Somewhere in between those two prime gaps there must be a prime at which the gap size decreases; a strong prime larger than our original strong prime. Hence there are infinitely many strong primes.