Cyclic quadratic residues

In summary, the conversation discusses a residue relation involving cyclic quadratic residues and primes. It is observed that the sum of all such residues is either 0 or 1 modulo the prime. Examples are given for different primes, including one where the sum of all residues is 4 times the prime. The conversation also mentions an interesting sequence related to the Fibonacci sequence and how it behaves differently in different moduli.
  • #1
ramsey2879
841
3
I also wonder about an other interesting residue relation

Let P be a prime,

let [tex] a^{2^n}[/tex] be called a cyclic quadratic residue if there is integer m dependent on [tex]a[/tex] such that [tex] a^{2^{n + mp}} = a^{2^n}[/tex] for all integers [tex]p \mod P[/tex]
It seems that the sum of all such cylic residues is either 0 or 1 mod P
For instance for P = 17 the only cyclic residue is 1 but for P = 37
there are the cyclic sequences
33 16 34 9 7 12 33 ...
10 26 10 ...
1 ...
and the sum of all these numbers, not including repetitions is 4*37.
 
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  • #2
Take the first 5 squares modulo 11: 1,4,9,5,3. Now square these numbers: Presto! We have them all back again 1,5,4,3,9. And the total is 22=11x2.
 
  • #3
ramsey2879 said:
I also wonder about an other interesting residue relation

Let P be a prime,

let [tex] a^{2^n}[/tex] be called a cyclic quadratic residue if there is integer m dependent on [tex]a[/tex] such that [tex] a^{2^{n + mp}} = a^{2^n}[/tex] for all integers [tex]p \mod P[/tex]
It seems that the sum of all such cylic residues is either 0 or 1 mod P
For instance for P = 17 the only cyclic residue is 1 but for P = 37
there are the cyclic sequences
33 16 34 9 7 12 33 ...
10 26 10 ...
1 ...
and the sum of all these numbers, not including repetitions is 4*37.
Sorry I wasn't clear I mean let S(1) = k mod p, S(n) = S(n-1)^2 mod p. this sequence does not become cyclic until S(i) = S(i+j) and i > 1 so not all quadratic residues are necessarily cyclic quadratic residues. if p = 11 the cyclic sequences are 4,5,3,9,4,5,3,9 ... and 1,1,1,1,..
So all 5 residues are cyclic quadratic residues.
There are other related sequences such as S(n) = S(n-1)^2 - 2 which are also interesting because it is the sequence A(n) = F(2^n)/F(2^(n-1)) where F = the fibonacci sequences.
F(4) = 3 F(8) = 21, 21/3 = 7 = 3^2 -2 F(16)/F(8) = 987/21 = 47 = 7*7 - 2, etc which in mod 11 is 3,7,3,7,3,7,3,7,..., but in mod 17 is 3,7,13,14,7,13,14 ... where 7,13,and 14 sum to 34
 
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What are cyclic quadratic residues?

Cyclic quadratic residues are a type of mathematical concept that relates to modular arithmetic and the properties of quadratic residues. They are numbers that have certain patterns when raised to different powers modulo a given number.

How are cyclic quadratic residues related to cyclic groups?

Cyclic quadratic residues are closely related to cyclic groups, as they are defined as the elements of a cyclic group that have a specific property when raised to certain powers modulo a given number. In fact, the set of cyclic quadratic residues forms a subgroup of the cyclic group.

What is the importance of studying cyclic quadratic residues?

The study of cyclic quadratic residues has many applications in number theory, cryptography, and other areas of mathematics. They can also provide insight into the properties of prime numbers and help solve certain mathematical problems.

How can one determine if a number is a cyclic quadratic residue modulo a given number?

There are various methods for determining if a number is a cyclic quadratic residue modulo a given number. One common method is to use the Legendre symbol, which can be calculated using the properties of quadratic residues and the properties of modular arithmetic.

What is the relationship between cyclic quadratic residues and Euler's criterion?

Euler's criterion is a theorem that relates to quadratic residues and the values of the Legendre symbol. This theorem states that if a is a quadratic residue modulo a prime number p, then a is congruent to a power of p modulo p. This is closely related to the properties of cyclic quadratic residues.

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