1742 On June 7th, German amateur mathematician Goldbach wrote to the great mathematician Euler at that time, and put forward the following conjecture:

(a) any n? Even number 6 can be expressed as the sum of two odd prime numbers.

(b) any n? The odd number 9 can be expressed as the sum of three odd prime numbers.

This is the famous Goldbach conjecture. Since Fermat put forward this conjecture, many mathematicians have been trying to conquer it, but they have not succeeded. Of course, some people have done some specific verification work, such as:

6 = 3 + 3, 8 = 3 + 5, 10 = 5 + 5 = 3 + 7, 12 = 5 + 7, 14 = 7 + 7 = 3 + 1 1,

16 = 5+ 1 1, 18 = 5+ 13, ...

Someone checked the even numbers within 33× 108 and above 6 one by one, and Goldbach conjecture (a) was established. However, the mathematical proof of lattice test needs the efforts of mathematicians. At present, the best result is proved by China mathematician Chen Jingrun in 1966, which is called Chen's theorem? "Any large enough even number is the sum of a prime number and a natural number, and the latter is just the product of two prime numbers." This result is often called a big even number and can be expressed as "1+2".

Before Chen Jingrun, the progress of even numbers can be expressed as the sum of the products of S prime numbers and T prime numbers (referred to as the "s+t" problem) as follows:

1920, Bren of Norway proved "9+9".

1924, Rademacher proved "7+7".

1932, Esterman of England proved "6+6".

1937, Ricei of Italy proved "5+7", "4+9", "3+ 15" and "2+366" successively.

1938, Byxwrao of the Soviet Union proved "5+5".

1940, Byxwrao of the Soviet Union proved "4+4".

1948, Hungary's benevolence and righteousness proved "1+c", where c is the number of nature.

1956, Wang Yuan of China proved "3+4".

1957, China and Wang Yuan successively proved "3+3" and "2+3".

1962, Pan Chengdong of China and Barba of the Soviet Union proved "1+5".

Wang Yuan of China proved "1+4".

1965, Byxwrao and vinogradov Jr of the Soviet Union and Bombieri of Italy proved "1+3".

1966, China Chen Jingrun proved "1+2".

Who will finally overcome the problem of "1+ 1"? It is still unpredictable.

Briefly introduce the most famous Goldbach conjecture, I hope it will help you.