Aryabhata
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 Sep 27 comment Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular @Americo: It is _60_a = 5n^2 + 5n blah. Sep 27 comment Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular @Hans: The numbers in the sequence are of the from $(n^2 + n)/12$, where $x = 2n+1$. So it could be anything. Sep 27 answered Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular Sep 27 revised Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular added 138 characters in body; edited title; deleted 1 characters in body; added 1 characters in body; edited body Sep 27 comment Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular @Charles: You can change your question by giving the recurrence relation here and asking how it can be dervied. I will go ahead and edit your question. Sep 27 comment Recurrence relation for $a_{n}$ where $6a_{n}$ and $10a_{n}$ are both triangular What exactly do you mean by characterize? Is the recurrence relation given in your link to A180926 not sufficient? Sep 27 comment Find the sum to n terms of the series $\displaystyle \frac{1} {1.2.3.4} + \frac{1} {2.3.4.5} + \frac{1} {3.4.5.6}$ @Branimir: You are welcome! And I see you joined today, welcome to this site :-) Sep 27 awarded Civic Duty Sep 27 comment Find the sum to n terms of the series $\displaystyle \frac{1} {1.2.3.4} + \frac{1} {2.3.4.5} + \frac{1} {3.4.5.6}$ +1: Even though the question says first n terms, this can easily be adapted for that. Sep 27 answered $k^{2}+(k+1)^{2}$ being a perfect square for infinitely many $k$ Sep 26 comment How to build a linear equation system? Are you trying to create test cases for your linear equation solver? If so, you could just generate the equations randomly and then verify the solution given by your solver by substitution into the original equations. Sep 25 comment How do I solve inequalities of the form $\left|\frac{f(x)}{g(x)}\right| \geq 1$? @mweerden: Well it amounts to finding the points where h(x) = (f(x)+g(x))(f(x)-g(x)) is non-negative. In case f(x) and g(x) are linear, this can easily be done without pen and paper! In some sense, there are fewer cases to consider here. Sep 25 answered Is there possibly a largest prime number? Sep 25 comment How is this series in denominator converted to a series in numerator? @Harpreet: No worries! btw, Welcome to this site. I hope you will find it useful. Sep 25 comment How is this series in denominator converted to a series in numerator? @Mariano: I was expecting the OP will do it himself... Anyway, I went ahead and made the change. Sep 25 revised How is this series in denominator converted to a series in numerator? math formatting Sep 25 comment How is this series in denominator converted to a series in numerator? @Harpreet: Use the dollar signs and latex between them. Example $x^2+y^2=z^2$ looks like $x^2+y^2=z^2$ Sep 25 revised Formally proving that a function is $O(x^n)$ added condition that a > 0 Sep 25 comment How is this series in denominator converted to a series in numerator? @Isaac: I interpreted it the same way too and added an answer with that interpretation. Sep 25 answered How is this series in denominator converted to a series in numerator?