While I am not sure about the year, the first such proof was provided by Euclid - and the proof is surprisingly simple!
This can be an extension to the proof that there are infinitely many prime numbers. If there are infinitely many prime numbers, then there are also infinitely many PRODUCTS of prime numbers. Those numbers that are the product of 2 or more prime numbers are not prime numbers.
There are infinitely many prime numbers and therefore they cannot be listed.There are infinitely many prime numbers and therefore they cannot be listed.There are infinitely many prime numbers and therefore they cannot be listed.There are infinitely many prime numbers and therefore they cannot be listed.
Since there are infinitely many prime numbers there are infinitely many sets of three prime numbers and so there are infinitely many products.
As there are infinitely many primes (as Euclid proved circa 300 BC) and not all of them are (or can be) known, it is impossible to answer this question.
There are infinitely many!
There are infinitely many prime numbers, and also infinitely many twin primes so there is no answer to the question.
The question does not make sense. There are not 500 prime numbers but infinitely many!
The question, "the" three odd prime numbers, is wrong. There are much more than three odd prime numbers - in fact, infinitely many. There are infinitely many prime numbers, and all except the number 2 are odd.
There are infinite prime numbers as there is infinite numbers. You cannot limit the counting of primes.
There are infinitely many prime numbers which are greater than 30.
There are infinitely many prime numbers. There is only one even prime number, which is 2, because all other even numbers are divisible by 2 and thus are not prime. So, there are infinitely many odd prime numbers and only one even prime number.
Infinitely many numbers are relatively prime to 37. Because 37 is a prime number, all other numbers are relatively prime to it.