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A cluster prime is a prime p such that every even natural number k ≤ p − 3 is the difference of two primes not exceeding p. 3, 5, 7, 11, 13, 17, 19, 23, ... (OEIS: A038134) All odd primes between 3 and 89, inclusive, are cluster primes. The first 10 primes that are not cluster primes are: 2, 97, 127, 149, 191, 211, 223, 227, 229, 251.
a lucky prime. [3] the sum of five consecutive primes (7 + 11 + 13 + 17 + 19). a Heegner number. [4] a Pillai prime since 18! + 1 is divisible by 67, but 67 is not one more than a multiple of 18. [5] palindromic in quinary (232 5) and senary (151 6). a super-prime. (19 is prime) an isolated prime. (65 and 69 are not prime) a sexy prime with 61 ...
The existence of arbitrarily large prime gaps can be seen by noting that the sequence ! +,! +, …,! + consists of composite numbers, for any natural number . [67] However, large prime gaps occur much earlier than this argument shows. [68]
One way to classify composite numbers is by counting the number of prime factors. A composite number with two prime factors is a semiprime or 2-almost prime (the factors need not be distinct, hence squares of primes are included). A composite number with three distinct prime factors is a sphenic number. In some applications, it is necessary to ...
Ω(n), the prime omega function, is the number of prime factors of n counted with multiplicity (so it is the sum of all prime factor multiplicities). A prime number has Ω(n) = 1. The first: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37 (sequence A000040 in the OEIS). There are many special types of prime numbers. A composite number has Ω(n) > 1.
The original, called Mersenne's conjecture, was a statement by Marin Mersenne in his Cogitata Physico-Mathematica (1644; see e.g. Dickson 1919) that the numbers were prime for n = 2, 3, 5, 7, 13, 17, 19, 31, 67, 127 and 257 (sequence A109461 in the OEIS), and were composite for all other positive integers n ≤ 257.
The table is complete up to the maximum norm at the end of the table in the sense that each composite or prime in the first quadrant appears in the second column. Gaussian primes occur only for a subset of norms, detailed in sequence OEIS: A055025. This here is a composition of sequences OEIS: A103431 and OEIS: A103432.
The table below lists the largest currently known prime numbers and probable primes ... 67 4×3 9214845 + 1 10 September 2024 4,396,600 68 9145334×3 9145334 + 1