User Calvin Lin - Mathematics Stack Exchange

367 votes

118 answers

38k views

Collection of surprising identities and equations.

asked Sep 26, 2013 at 0:45

39 votes

3 answers

2k views

When is $2^n \pm 1$ a perfect power

asked Sep 21, 2013 at 19:37

24 votes

2 answers

1k views

For polynomial $f$, does $f$(rational) = rational$^2$ always imply that $f(x) = g(x)^2$?

asked Jul 3, 2013 at 23:28

22 votes

2 answers

862 views

Odd perfect squares whose decimal representation consist only of 1's and o's

asked Jul 5, 2013 at 22:47

20 votes

2 answers

709 views

For what $n$ can we find a degree $\leq n-2$ polynomial such that $P(i) \in \{0 , 1 \}$ for $i \in [n]$, but not all identical.

asked Feb 22, 2023 at 1:12

19 votes

5 answers

20k views

Order of nontrivial elements is 2 implies Abelian group

asked Jan 11, 2013 at 1:14

16 votes

0 answers

437 views

Number of circles in configuration

asked Jan 9, 2013 at 8:11

16 votes

2 answers

1k views

Comparing sums of surds without any aids

asked Aug 15, 2013 at 0:42

11 votes

2 answers

2k views

Resource for Vieta root jumping

asked Jan 28, 2013 at 6:35

10 votes

2 answers

637 views

Possible values of prime gaps

asked Apr 12, 2013 at 19:18

10 votes

1 answer

232 views

Possible values of difference of 2 primes

asked Aug 7, 2013 at 22:19

7 votes

1 answer

404 views

Expected value of $|H-T|$ in $n$ coin flips

asked May 13, 2013 at 18:54

5 votes

4 answers

1k views

Different meanings of math terms in different countries

asked Jul 18, 2013 at 19:11

5 votes

1 answer

232 views

Integer ordered pairs (x,y) satisfying $x^2 - y! = N$

asked Oct 2, 2013 at 14:33

4 votes

1 answer

332 views

Integer solutions to $ n^2 + 1 = 2 \times 5^m$

asked Feb 16, 2015 at 0:56

1 vote

1 answer

167 views

Density of $ \{rn^2\} $

asked Jun 27, 2017 at 13:15

1 vote

2 answers

342 views

Find all positive integers $n$ for which the equation $x + y + u + v = n \sqrt{ xyuv }$ has a solution in positive integers. [closed]

asked Mar 28, 2020 at 19:06

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17 Questions

Collection of surprising identities and equations.

When is $2^n \pm 1$ a perfect power

For polynomial $f$, does $f$(rational) = rational$^2$ always imply that $f(x) = g(x)^2$?

Odd perfect squares whose decimal representation consist only of 1's and o's

For what $n$ can we find a degree $\leq n-2$ polynomial such that $P(i) \in \{0 , 1 \}$ for $i \in [n]$, but not all identical.

Order of nontrivial elements is 2 implies Abelian group

Number of circles in configuration

Comparing sums of surds without any aids

Resource for Vieta root jumping

Possible values of prime gaps

Possible values of difference of 2 primes

Expected value of $|H-T|$ in $n$ coin flips

Different meanings of math terms in different countries

Integer ordered pairs (x,y) satisfying $x^2 - y! = N$

Integer solutions to $ n^2 + 1 = 2 \times 5^m$

Density of $ \{rn^2\} $

Find all positive integers $n$ for which the equation $x + y + u + v = n \sqrt{ xyuv }$ has a solution in positive integers. [closed]