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Oct
29
comment A geometric assembly: Triangle, circle, square, pentagon.
I think I've seen somewhere the second problem about the inverse and I vaguely remember the value 12 as limit.
Oct
24
comment $27 | (2x+1)^2 \implies 2x$ is a multiple of 9?
@RyanYu Then edit the title of your question.
Oct
3
comment Is this a isomorphism $(\mathbb Z,+) \to (Z,+)$ where $\varphi(n) = 2n$? Why not?
You are missing that there is no n such as φ(n)=1. Or φ(n)=3. So, the image of φ is not Z but a subset. You say " for every element in Z in the first group there is a element 2n in the second group." Right. But for every element y in Z in the second group is there is an element n in the first group such as φ(n)=y?
Oct
3
comment Solving $p_1^{e_1} p_2^{e_2}…p_k^{e_k}=e_1^{p_1} e_2^{p_2}…e_k^{p_k}$
@Tom-Tom I'm not sure but I see 4 or 5 adjacent related seqeunces, so I guess no. The "last modified" footer seems to in all OEIS sequences.
Oct
3
comment Solving $p_1^{e_1} p_2^{e_2}…p_k^{e_k}=e_1^{p_1} e_2^{p_2}…e_k^{p_k}$
@AnalysisIncarnate No, only just now searched for it. It doesn't have a date but several adjacent sequences were created by the same author (Olivier)
Oct
3
comment Solving $p_1^{e_1} p_2^{e_2}…p_k^{e_k}=e_1^{p_1} e_2^{p_2}…e_k^{p_k}$
@Tom-Tom and possible combinations of the above 3. (e.g. 2^4 * 3*3 * 5^7 * 7^5). Or what you said with "cycles of length 1 or 2" and the exception for 2^4.
Oct
3
comment Solving $p_1^{e_1} p_2^{e_2}…p_k^{e_k}=e_1^{p_1} e_2^{p_2}…e_k^{p_k}$
OEIS sequence A008478
Oct
3
comment Solving $p_1^{e_1} p_2^{e_2}…p_k^{e_k}=e_1^{p_1} e_2^{p_2}…e_k^{p_k}$
There's also 2^3 * 3^2. And (2^17 * 17^2) * (3^31 * 31^3), ...
Oct
3
comment Quick and painless definition of the set of real numbers
Continued fractions might be a good idea.
Aug
26
comment How many ways to generate unique multiplication result from given set?
There are 5 elevens, 5 sevens, 4 fives, 3 threes and 3 twos. And there are in total 5 distinct primes in the set. The (-N-1) calculation is needed because you don't include the "one factor" and the "zero factor" multiplications.
Aug
26
comment How many ways to generate unique multiplication result from given set?
If pi are the distinct prime numbers in the (multi)set and ni are the number of times the respective pi appears, then the result is Product(ni+1) - N - 1 (oh and N is the number of disticnt primes.) So for you last example would be (5+1)*(5+1)*(4+1)*(3+1)*(3+1) - 5 - 1 = 2874
Aug
26
comment How to show the convergence of this infinite series: $\frac{x}{1+x}- \frac{x^2}{1+x^2}+ \frac{x^3}{1+x^3}\dots$
@mike the question has: Given: 0<x<1
Jul
31
revised Are all fields vector spaces?
grammar corrections. Not sure about the phrasing of the last sentence, seems still wrong.
Jul
31
suggested approved edit on Are all fields vector spaces?
Apr
4
awarded  Excavator
Apr
4
revised What does $2^x$ really mean when $x$ is not an integer?
correction on exponents formula
Apr
4
suggested approved edit on What does $2^x$ really mean when $x$ is not an integer?
Mar
23
comment Relationship between logarithms and harmonic series
What is log(x)n? Is it log of n with base x? Or logx (and in what base?) multiplied by n?
Nov
4
comment Is 10 closer to infinity than 1?
Perhaps you can add a section on Surreal Numbers where we have both the order-theoretic approach and addition-subtraction between infinite numbers. And the (simplest) infinite number ω is well defined and so are ω-10 and ω-1 and we can prove that ω-10 < ω-1.
Oct
27
comment Infinite groups of order $2$
Why don't you provide your attempt to solve it?