90 Finding a primitive root of a prime number 33 Getting the sequence $\{1, 0, -1, 0, 1, 0, -1, 0, \ldots\}$ without trig? 30 If $n$ is an odd natural number, then $8$ divides $n^{2}-1$ 18 Getting the sequence $\{1, 0, -1, 0, 1, 0, -1, 0, \ldots\}$ without trig? 12 preservation of completeness under homeomorphism

### Reputation (4,638)

 +20 If a plane is divided by $n$ lines, then it is possible to color the regions formed with only two colors. +20 Finding a primitive root of a prime number +10 Getting the sequence $\{1, 0, -1, 0, 1, 0, -1, 0, \ldots\}$ without trig? +10 Showing $\rho (x,y)=\frac{d(x,y)}{1+d(x,y)}$ is a metric

### Questions (4)

 5 Can non-existent set still be infinite? 3 Polynomial boundaries 2 The name for the quotient property. 1 Irreducible variety

### Tags (90)

 90 modular-arithmetic 52 general-topology × 20 90 number-theory 51 pattern-recognition × 2 90 prime-numbers 45 elementary-number-theory × 8 90 cryptography 30 square-numbers 56 sequences-and-series × 8 22 discrete-mathematics × 6