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Cocopuffs
  • Member for 10 years, 2 months
  • Last seen more than 3 years ago
32 votes
Accepted

How did Ramanujan get this result?

29 votes
Accepted

Prove that every number ending in a $3$ has a multiple which consists only of ones.

29 votes
Accepted

Prove that $2^n < \binom{2n}{n} < 2^{2n}$

26 votes

"Negative" versus "Minus"

22 votes

Prove that $ U(n^2−1)$ is not cyclic

18 votes
Accepted

Is it assumable that $2^{1/12}$ is irrational because $2^{1/2}$ is?

15 votes
Accepted

Non-Decreasing Digits

15 votes
Accepted

Simple number theory problem

15 votes

Finite set of zero-divisors implies finite ring

15 votes
Accepted

Find coefficient of $x^{100}$ in the power series expansion of $\frac{1}{(1-x)(1-2x)(1-3x)}$

15 votes
Accepted

Prove limit of $\frac1{n+1}+\frac1{n+2}+\ldots+\frac1{n+n}$ exists and lies between $0$ and $1$.

13 votes

Why $y^2-x^3-x^2$ is irreducible?

13 votes
Accepted

How do we know that $|i!| = \sqrt{\pi \operatorname{csch} \pi}$?

13 votes
Accepted

Eigenvalues and determinant of conjugate, transpose and hermitian of a complex matrix.

12 votes
Accepted

Computing $ \sum_{m=0}^{\infty} \sum_{n=0}^{\infty}\frac{1}{\Gamma \left(\frac{m+n}{2}\right)\Gamma \left(\frac{1+m+n}{2} \right)}$

11 votes
Accepted

proving that a number is a perfect square

11 votes
Accepted

infinite number of irreducible polynomials in $\mathbb{Z}/2{\mathbb Z}[X]$

11 votes

Proving irreducibility of $x^6-72$

10 votes
Accepted

Not divisible by $2,3$ or $5$ but divisible by $7$

9 votes

How do I solve this problem?

9 votes
Accepted

Tricky proof for a simple statement

9 votes

Value of $P(12)+P(-8)$ if $P(x)=x^{4}+ax^{3}+bx^{2}+cx+d$, $P(1)=10$, $P(2)=20$, $P(3)=30$

9 votes
Accepted

Prove $\sum_{i=1}^n$$w_i^2\geq\frac{1}{n}$ given $\sum_{i=1}^n w_i=1$

8 votes

How to derive a closed form of a simple recursion?

8 votes

Proving $\sqrt{2}\in\mathbb{Q_7}$?

8 votes
Accepted

Complex number with z to the power of 4

7 votes

How to prove $G_2$ is a normal subgroup of $G_1\times G_2$?

7 votes

Big List of Fun Math Books

7 votes
Accepted

Chain rule and inverse in matrix calculus

7 votes
Accepted

Flipping Cards Probability

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