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Rowland (2008) proved that this sequence contains only ones and prime numbers. However, it does not contain all the prime numbers, since the terms gcd(n + 1, a n) are always odd and so never equal to 2. 587 is the smallest prime (other than 2) not appearing in the first 10,000 outcomes that are different from 1. Nevertheless, in the same paper ...
The first term of the third sequence is 0 because p 0 # = 1 (we also let p 0 = 1, see Prime_number#Primality_of_one, hence the first term of the fourth sequence is 1) is the empty product, and thus p 0 # + 1 = 2, which is prime. Similarly, the first term of the first sequence is not 1 (hence the first term of the second sequence is also not 2 ...
p n # as a function of n, plotted logarithmically.. For the n th prime number p n, the primorial p n # is defined as the product of the first n primes: [1] [2] # = =, where p k is the k th prime number.
The first such distribution found is π(N) ~ N / log(N) , where π(N) is the prime-counting function (the number of primes less than or equal to N) and log(N) is the natural logarithm of N. This means that for large enough N , the probability that a random integer not greater than N is prime is very close to 1 / log( N ) .
If n is a power of an odd prime number the formula for the totient says its totient can be a power of two only if n is a first power and n − 1 is a power of 2. The primes that are one more than a power of 2 are called Fermat primes , and only five are known: 3, 5, 17, 257, and 65537.
Every Euclid number is congruent to 3 modulo 4 since the primorial of which it is composed is twice the product of only odd primes and thus congruent to 2 modulo 4. This property implies that no Euclid number can be a square. For all n ≥ 3 the last digit of E n is 1, since E n − 1 is divisible by 2 and 5.
A prime sieve or prime number sieve is a fast type of algorithm for finding primes. There are many prime sieves. The simple sieve of Eratosthenes (250s BCE), the sieve of Sundaram (1934), the still faster but more complicated sieve of Atkin [1] (2003), sieve of Pritchard (1979), and various wheel sieves [2] are most common.
The prime constant is the real number whose th binary digit is 1 if is prime and 0 if is composite or 1. In other words, ρ {\displaystyle \rho } is the number whose binary expansion corresponds to the indicator function of the set of prime numbers .