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Feb
21
revised How many different numbers can be written if each used digit symbol is used at least 2 times?
added 21 characters in body
Feb
21
comment How many different numbers can be written if each used digit symbol is used at least 2 times?
Thanks a lot for answer . I edited my question with wonderful discover for $P(n,d)$. Could you please share your comments on my last edit?
Feb
21
revised How many different numbers can be written if each used digit symbol is used at least 2 times?
added 2166 characters in body
Feb
19
revised How many different numbers can be written if each used digit symbol is used at least 2 times?
added 1 character in body
Feb
19
revised How many different numbers can be written if each used digit symbol is used at least 2 times?
edited body
Feb
19
revised How many different numbers can be written if each used digit symbol is used at least 2 times?
edited body
Feb
19
asked How many different numbers can be written if each used digit symbol is used at least 2 times?
Jan
15
comment What is lower limit condition of a surface of a tetrahedron?
Can we have only one lower condition ? or impossible. If it exists, it should be cyclic .for example, the lower condition could be $|S_2-S_3|+|S_3-S_4|+|S_2-S_4|<S_1$ but I do not know if it exists such cyclic condition or how to prove that it is impossible to eliminate 3 necessary condition into one condition.
Jan
14
revised What is lower limit condition of a surface of a tetrahedron?
edited title
Jan
13
asked What is lower limit condition of a surface of a tetrahedron?
Jan
11
revised Proof that $\sum\limits_{k=1}^nk^2 = \frac{n(n+1)(2n+1)}{6}$?
I corrected mistyped 3 as 2
Jan
7
revised How can I solve the differential equation $y'+y^{2}=f(x)$?
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Jan
7
revised How can I solve the differential equation $y'+y^{2}=f(x)$?
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Jan
5
comment $e^x(\ln x-c) =\sum \limits_{k=0}^\infty \frac{ x^{k} \Gamma'(k+1)}{ (k!)^2}$ Is it correct result?
I have asked a question in math.overflow that is related to your computation a long time ago. mathoverflow.net/questions/227642/… . I saw your comment about your result. Thanks a lot for your comment. It is very supporting comment but the question is voted as off-topic. . I am sure that it is very interesting and helpful topic question. Could you please edit my question in overflow for more formal mathematical perspective? Thanks
Jan
5
awarded  Yearling
Jan
4
revised What is the derivative of: $f(x)=x^{2x^{3x^{4x^{5x^{6x^{7x^{.{^{.^{.}}}}}}}}}}$?
added 1 character in body
Dec
30
revised What is the derivative of: $f(x)=x^{2x^{3x^{4x^{5x^{6x^{7x^{.{^{.^{.}}}}}}}}}}$?
added 72 characters in body
Dec
29
revised What is the derivative of: $f(x)=x^{2x^{3x^{4x^{5x^{6x^{7x^{.{^{.^{.}}}}}}}}}}$?
added 673 characters in body
Dec
29
revised What is the derivative of: $f(x)=x^{2x^{3x^{4x^{5x^{6x^{7x^{.{^{.^{.}}}}}}}}}}$?
deleted 9 characters in body
Dec
29
revised What is the derivative of: $f(x)=x^{2x^{3x^{4x^{5x^{6x^{7x^{.{^{.^{.}}}}}}}}}}$?
added 151 characters in body