Prove that $a$ is always odd for when $a \% 2=1$
7043
mod [= remainder] operation (and relation), name and meaning
68824
Show that $\frac{(3^{77}-1)}{2}$ is odd and composite
62382
I suppose $(a,m)=(a-1,m)=1$, show that $1+a+a^2+\ldots+a^{\phi(m)-1}\equiv0\pmod m$
45037
Show $(2^m-1,2^n+1)=1$ if $m$ is odd
136403
Prove that $\sqrt{a}\leq\frac{1+a}{2}$
92057
Prove that for every odd integer n, there is a group...
31895
Prove that if $a$ and $b$ are odd, coprime numbers, then $\gcd(2^a +1, 2^b +1) = 3$
83307
If $n\mid a^2-1$, $n$ an odd integer, show $n = \gcd(a-1, n)\gcd(a+1, n)$
34666
Prove that the expression cannot be a power of 2
125267
Prove that $2^{1/2}$ is irrational
128199
Proving gcd(a, a+2) is 1 or 2 for every integer a?
152039
Prove that $a^{2^n}=1 \mod 2^{n+2}$
157294
Prove that if $n>1$ is odd, then $1^n+2^n+3^n+\ldots+(n-1)^n$ is divisible by $n$
158862
Show that $a(-1) = (-1)a = -a $.
43913
Prove that if $A^*+A=AA^*$ then $A$ is normal
111515
Proving that $-a=(-1)\cdot a$
66703
Show that $8 \mid (a^2-b^2)$ for $a$ and $b$ both odd