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A counterexample is an example that disproves a mathematical conjecture or a purported theorem. For example, the Peterson graph is a counterexample to many seemingly plausible conjectures in Graph Theory.

1 vote
1 answer
358 views

Primality test for numbers of the form $4k+3$

Can you prove or disprove the following claim: Let $n$ be a natural number of the form $4k+3$ , and let $c$ be the smallest odd prime such that $\binom{c}{n}=-1$ , where $\binom{}{}$ denotes a Jacobi …
Pedja's user avatar
  • 2,661
10 votes
0 answers
631 views

Primality testing using Chebyshev polynomials

Can you provide a proof or a counterexample for the claim given below? Inspired by an alternative definition of the Frobenius primality test which is given in this paper I have formulated the followin …
Pedja's user avatar
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4 votes
1 answer
182 views

Primality test for specific class of $N=8k \cdot 3^n-1$

This question is related to my previous question. Can you prove or disprove the following claim: Let $P_m(x)=2^{-m}\cdot \left(\left(x-\sqrt{x^2-4}\right)^{m}+\left(x+\sqrt{x^2-4}\right)^{m}\right)$ …
Pedja's user avatar
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2 votes
1 answer
363 views

Primality test for specific class of $N=8kp^n-1$

My following question is related to my question here Can you provide a proof or a counterexample for the following claim : Let $P_m(x)=2^{-m}\cdot \left(\left(x-\sqrt{x^2-4}\right)^{m}+\left(x+ …
Pedja's user avatar
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5 votes
1 answer
332 views

Conjectured primality test for specific class of $N=k \cdot 6^n+1$

I have tested this claim for many random values of $k$ and $n$ and there were no counterexamples . Test implementation in PARI/GP without directly computing cyclotomic polynomials. …
Pedja's user avatar
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9 votes
1 answer
416 views

Conjectured primality test for specific class of $N=4kp^n+1$

Can you provide a proof or counterexample for the following claim? Let $P_m(x)=2^{-m}\cdot((x-\sqrt{x^2-4})^m+(x+\sqrt{x^2-4})^m)$ . Let $N= 4kp^{n}+1 $ where $k$ is a positive natural number , …
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  • 2,661
3 votes
0 answers
263 views

Conjectured primality test for numbers of the form $N=4 \cdot 3^n-1$

This is a repost of this question. Can you provide proof or counterexample for the claim given below? Inspired by Lucas-Lehmer primality test I have formulated the following claim: Let $P_m(x)=2^{-m} …
Pedja's user avatar
  • 2,661
2 votes
1 answer
833 views

Primality test for generalized Fermat numbers

I have tested this claim for many random values of $b$ and $n$ and there were no counterexamples. A command line program that implements this test can be found here. …
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3 votes
1 answer
383 views

Primality test for specific class of $N=k \cdot b^n-1$

This question is successor of Compositeness test for specific class of $N=k \cdot b^n-1$ . Can you provide a proof or a counterexample to the following claim : Let $P_m(x)=2^{-m}\cdot \left(\left …
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11 votes
2 answers
910 views

Primality test for specific class of Proth numbers

I have tested this claim for many random values of $k$ and $n$ and there were no counterexamples . Note that for $k=1$ we have Inkeri's primality test for Fermat numbers . …
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2 votes
0 answers
305 views

Conjectured initial values of Inkeri's primality test for Fermat numbers

This is a repost of this question . Can you provide a proof or a counterexample to the claim given below ? First , we shall give a definition of the Inkeri's primality test for Fermat numbers : …
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66 votes
3 answers
6k views

Chebyshev polynomials of the first kind and primality testing

I have tested this claim up to $5 \cdot 10^4$ and there were no counterexamples . EDIT Algorithm implementation in Sage without directly computing $T_n(x)$ . …
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5 votes
0 answers
586 views

Primality test for specific class of generalized Fermat numbers

I have verified this claim for $p \in [7,5000]$ with $n \in [2,10]$ and there were no counterexamples . …
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