In 1752 Goldbach conjectured that every odd integer can be written in the form p + 2a^2, where p is unity or a prime and a is allowed to be zero.
This conjecture is found to be false - there are only two known composite exceptions, 5777 (=53*109) being one of them.

Please find the other, it is below 99,999.

The link below gives the answer as well as some history and interesting math.

Posted by xdog on 2015-03-03 11:38:24