Question

Why is the following estimation true?

score 43 · Answer 1 · 2026-03-23 05:30:47

43

Views

Why is the following estimation true?

Published on 23 Mar 2026 - 5:30

score 171 · Answer 2 · 2026-03-25 06:28:41

171

Views

Prove that there exist infintely many primes $p$ with $p\equiv2$ or $-2 \pmod{5}$

Published on 25 Mar 2026 - 6:28

score 58 · Answer 3 · 2026-03-19 21:45:02

58

Views

Characterize solutions of an equation involving the sum of divisors function and the Euler's totient function: Mersenne primes and Wagstaff primes

Published on 19 Mar 2026 - 21:45

score 53 · Answer 4 · 2026-03-25 02:53:31

53

Views

A non obvious example of a sequence $a(k)\cdot H_{b(k)}$ whose general term is integer many times, where $H_n$ denotes the $n$th harmonic number

Published on 25 Mar 2026 - 2:53

score 83 · Answer 5 · 2026-03-25 06:32:01

83

Views

Use Euler's Criterion to deduce that $5^{2^{2^{n}-1}}\equiv -1 \space \text{mod} \space p $

Published on 25 Mar 2026 - 6:32

score 51 · Answer 6 · 2026-03-22 07:53:20

51

Views

Deduce that $\left(\frac{2}{p}\right)=(-1)^{\frac{1}{2}(p-1)-k}$

Published on 22 Mar 2026 - 7:53

score 109 · Answer 7 · 2026-03-17 06:14:19

109

Views

Number of entries are not divisible by x in the n th row of triangle

Published on 17 Mar 2026 - 6:14

score 217 · Answer 8 · 2026-03-22 00:30:18

217

Views

Does Mathematica have a function for the composite numbers not divisible by a squared prime?

Published on 22 Mar 2026 - 0:30

score 72 · Answer 9 · 2026-03-23 04:56:44

72

Views

Why $n=4$ the only integer satisfying :$-1+2^{n²+n+41}$ to be prime from $n=0$ to $n=40$?

Published on 23 Mar 2026 - 4:56

score 54 · Answer 10 · 2026-03-22 20:24:56

54

Views

Approximation for $\prod\limits_{r<p\le P}\left( 1-\frac rp\right)^{-1}$

Published on 22 Mar 2026 - 20:24

score 169 · Answer 11 · 2026-03-22 20:55:56

169

Views

Why $\sum\frac{\mu(h)\mu(k)}{hk}\gcd(h,k)=\prod\limits_{p\le x}\left(1-\frac1p\right)$, where the sum enumerates the pairs $(h,k)$ of primes below $x$

Published on 22 Mar 2026 - 20:55

score 63 · Answer 12 · 2018-02-07 11:05:05

63

Views

Irrationality of $\sum\limits_{p}{\frac{1}{2^p}}$ over prime p-s

Published on 07 Feb 2018 - 11:05

score 106 · Answer 13 · 2026-03-14 19:29:04

106

Views

Two miscellaneous questions about equations involving the Euler's totient function and twin primes

Published on 14 Mar 2026 - 19:29

score 516 · Answer 14 · 2026-03-24 22:01:39

516

Views

What is the smallest prime factor of a composite number?

Published on 24 Mar 2026 - 22:01

score 564 · Answer 15 · 2026-03-20 19:31:48

564

Views

Raising an expression involving modulo operator to a power.

Published on 20 Mar 2026 - 19:31

List Question

Why is the following estimation true?

Prove that there exist infintely many primes $p$ with $p\equiv2$ or $-2 \pmod{5}$

Characterize solutions of an equation involving the sum of divisors function and the Euler's totient function: Mersenne primes and Wagstaff primes

A non obvious example of a sequence $a(k)\cdot H_{b(k)}$ whose general term is integer many times, where $H_n$ denotes the $n$th harmonic number

Use Euler's Criterion to deduce that $5^{2^{2^{n}-1}}\equiv -1 \space \text{mod} \space p $

Deduce that $\left(\frac{2}{p}\right)=(-1)^{\frac{1}{2}(p-1)-k}$

Number of entries are not divisible by x in the n th row of triangle

Does Mathematica have a function for the composite numbers not divisible by a squared prime?

Why $n=4$ the only integer satisfying :$-1+2^{n²+n+41}$ to be prime from $n=0$ to $n=40$?

Approximation for $\prod\limits_{r<p\le P}\left( 1-\frac rp\right)^{-1}$

Why $\sum\frac{\mu(h)\mu(k)}{hk}\gcd(h,k)=\prod\limits_{p\le x}\left(1-\frac1p\right)$, where the sum enumerates the pairs $(h,k)$ of primes below $x$

Irrationality of $\sum\limits_{p}{\frac{1}{2^p}}$ over prime p-s

Two miscellaneous questions about equations involving the Euler's totient function and twin primes

What is the smallest prime factor of a composite number?

Raising an expression involving modulo operator to a power.

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