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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.
All prime numbers from 31 to 6,469,693,189 for free download. Lists of Primes at the Prime Pages. The Nth Prime Page Nth prime through n=10^12, pi(x) through x=3*10^13, Random primes in same range. Interface to a list of the first 98 million primes (primes less than 2,000,000,000) Weisstein, Eric W. "Prime Number Sequences". MathWorld.
However, in this case, there is some fortuitous cancellation between the two factors of P n modulo 25, resulting in P 4k −1 ≡ 3 (mod 25). Combined with the fact that P 4k −1 is a multiple of 8 whenever k > 1, we have P 4k −1 ≡ 128 (mod 200) and ends in 128, 328, 528, 728 or 928.
The same prime factor may occur more than once; this example has two copies of the prime factor When a prime occurs multiple times, exponentiation can be used to group together multiple copies of the same prime number: for example, in the second way of writing the product above, 5 2 {\displaystyle 5^{2}} denotes the square or second power of 5 ...
The tables below list all of the divisors of the numbers 1 to 1000. ... 128 1 deficient, prime 128: 1, 2, 4, 8, 16, 32, 64, 128 8 255 127 deficient, composite 129:
Since q is a factor of 2 p − 1, for all positive integers c, q is also a factor of 2 pc − 1. Since p is prime and q is not a factor of 2 1 − 1, p is also the smallest positive integer x such that q is a factor of 2 x − 1. As a result, for all positive integers x, q is a factor of 2 x − 1 if and only if p is a factor of x.
The sum of Euler's totient function φ(x) over the first twenty integers is 128. [4] 128 can be expressed by a combination of its digits with mathematical operators, thus 128 = 2 8 − 1, making it a Friedman number in base 10. [5] A hepteract has 128 vertices. 128 is the only 3-digit number that is a 7th power (2 7).
All prime numbers are known to be solitary, as are powers of prime numbers. More generally, if the numbers n and σ( n ) are coprime – meaning that the greatest common divisor of these numbers is 1, so that σ( n )/ n is an irreducible fraction – then the number n is solitary (sequence A014567 in the OEIS ).