Question

Why is the following estimation true?

score 48 · Answer 1 · 2026-04-29 12:57:08

48

Views

Why is the following estimation true?

Published on 29 Apr 2026 - 12:57

score 172 · Answer 2 · 2026-05-10 20:53:17

172

Views

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

Published on 10 May 2026 - 20:53

score 67 · Answer 3 · 2026-05-07 11:33:09

67

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 07 May 2026 - 11:33

score 61 · Answer 4 · 2026-05-05 08:24:33

61

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 05 May 2026 - 8:24

score 87 · Answer 5 · 2026-05-10 22:09:21

87

Views

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

Published on 10 May 2026 - 22:09

score 56 · Answer 6 · 2026-05-02 01:15:23

56

Views

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

Published on 02 May 2026 - 1:15

score 116 · Answer 7 · 2026-05-06 11:32:56

116

Views

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

Published on 06 May 2026 - 11:32

score 225 · Answer 8 · 2026-05-05 10:31:08

225

Views

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

Published on 05 May 2026 - 10:31

score 79 · Answer 9 · 2026-05-03 03:45:43

79

Views

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

Published on 03 May 2026 - 3:45

score 58 · Answer 10 · 2026-04-20 03:50:08

58

Views

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

Published on 20 Apr 2026 - 3:50

score 179 · Answer 11 · 2026-05-07 03:53:59

179

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 07 May 2026 - 3:53

score 66 · Answer 12 · 2026-04-15 04:35:03

66

Views

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

Published on 15 Apr 2026 - 4:35

score 115 · Answer 13 · 2026-05-10 19:19:48

115

Views

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

Published on 10 May 2026 - 19:19

score 521 · Answer 14 · 2026-05-10 15:01:55

521

Views

What is the smallest prime factor of a composite number?

Published on 10 May 2026 - 15:01

score 571 · Answer 15 · 2026-05-05 04:05:08

571

Views

Raising an expression involving modulo operator to a power.

Published on 05 May 2026 - 4:05

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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