What is $1+2+4+8+16+...+2^n$?
2678
Values of $\sum_{n=0}^\infty x^n$ and $\sum_{n=0}^N x^n$
114506
Expansion of $(1+\sqrt{2})^n$
87589
Evaluate $\binom{n}{0}+\binom{n}{2}+\binom{n}{4}+...+\binom{n}{2k}$
67666
show that $a^2+b^2+c^2+2abc+3\ge (1+a)(1+b)(1+c)$
131310
Evaluating $\dfrac{1}{\sin(2x)} + \dfrac{1}{\sin(4x)} + \dfrac{1}{\sin(8x)} + \dfrac{1}{\sin(16x)}$
53725
Factor $(x+y)^4+x^4+y^4$
124248
$1+\frac {1}{4}(1+\frac {1}{4}) +\frac {1}{9}(1+\frac {1}{4} +\frac {1}{9})+....$
99502
Question on the coefficients of $(1+x+x^2+x^3+x^4)^{496}$
68725
Find expression for : $ S_n =\sum_{i=1}^{n} \frac{i}{i^4+i^2+1} $
115244
Integer solutions of $m^2+(m+1)^2=n^4+(n+1)^4$
100896
What is the sum of this? $ 1 + \frac12 + \frac13 + \frac14 + \frac16 + \frac18 + \frac19 + \frac1{12} +\cdots$
89705
How to solve $a_n = 2a_{n-1} + 1, a_0 = 0, a_1 = 1$?
113230
How can we factor $ q^4 + q^2 + 1$
106441
Find the value of $\binom{2000}{2} + \binom{2000}{5} + \binom{2000}{8} + \cdots \binom{2000}{2000}$
83641
The sum of the series $\frac{15}{16}+\frac{15}{16} \times \frac{21}{24}+\frac{15}{16} \times \frac{21}{24} \times \frac{27}{32}+\dots$
50050
A formula for the power sums: $1^n+2^n+\dotsc +k^n=\,$?
121918
Why is $5^{n+1}+2\cdot 3^n+1$ a multiple of $8$ for every natural number $n$?