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  2. Landau's problems - Wikipedia

    en.wikipedia.org/wiki/Landau's_problems

    Montgomery and Vaughan showed that the exceptional set of even numbers not expressible as the sum of two primes has a density zero, although the set is not proven to be finite. [9] The best current bounds on the exceptional set is E ( x ) < x 0.72 {\displaystyle E(x)<x^{0.72}} (for large enough x ) due to Pintz , [ 10 ] [ 11 ] and E ( x ) ≪ x ...

  3. Primality test - Wikipedia

    en.wikipedia.org/wiki/Primality_test

    If it is 1, then n may be prime. If a n −1 (modulo n) is 1 but n is not prime, then n is called a pseudoprime to base a. In practice, if a n −1 (modulo n) is 1, then n is usually prime. But here is a counterexample: if n = 341 and a = 2, then even though 341 = 11·31 is composite.

  4. Legendre's conjecture - Wikipedia

    en.wikipedia.org/wiki/Legendre's_conjecture

    Legendre's conjecture, proposed by Adrien-Marie Legendre, states that there is a prime number between and (+) for every positive integer. [1] The conjecture is one of Landau's problems (1912) on prime numbers, and is one of many open problems on the spacing of prime numbers.

  5. Euclid's lemma - Wikipedia

    en.wikipedia.org/wiki/Euclid's_lemma

    Any prime number is prime to any number it does not measure. [note 6] Proposition 30 If two numbers, by multiplying one another, make the same number, and any prime number measures the product, it also measures one of the original numbers. [note 7] Proof of 30 If c, a prime number, measure ab, c measures either a or b. Suppose c does not measure a.

  6. Number theory - Wikipedia

    en.wikipedia.org/wiki/Number_theory

    Number theory is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic functions.German mathematician Carl Friedrich Gauss (1777–1855) said, "Mathematics is the queen of the sciences—and number theory is the queen of mathematics."

  7. Safe and Sophie Germain primes - Wikipedia

    en.wikipedia.org/wiki/Safe_and_Sophie_Germain_primes

    A prime number q is a strong prime if q + 1 and q − 1 both have some large (around 500 digits) prime factors. For a safe prime q = 2p + 1, the number q − 1 naturally has a large prime factor, namely p, and so a safe prime q meets part of the criteria for being a strong prime. The running times of some methods of factoring a number with q as ...

  8. Prime number theorem - Wikipedia

    en.wikipedia.org/wiki/Prime_number_theorem

    In the second edition of his book on number theory (1808) he then made a more precise conjecture, with A = 1 and B = −1.08366. Carl Friedrich Gauss considered the same question at age 15 or 16 "in the year 1792 or 1793", according to his own recollection in 1849. [ 6 ]

  9. Literal (mathematical logic) - Wikipedia

    en.wikipedia.org/wiki/Literal_(mathematical_logic)

    In mathematical logic, a literal is an atomic formula (also known as an atom or prime formula) or its negation. [1] [2] The definition mostly appears in proof theory (of classical logic), e.g. in conjunctive normal form and the method of resolution. Literals can be divided into two types: [2] A positive literal is just an atom (e.g., ).