Questions tagged [ramanujan-summation]

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Ramanujan summation is a technique invented by the mathematician Srinivasa Ramanujan for assigning a value to infinite divergent series.

63 questions
0 votes 0 answers 51 views

Count the number of ordered triples of positive integers whose product is not greater than a given number?

Given N, count the number of ordered triplets(a,b,c) whose product $abc \leq N$. I have found the series here . But I am not sure I understand Benoit Cloitre work which proposed an efficent way to ... user avatar Bob McCheese
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1 vote 0 answers 51 views

Grandi's series

So a couple of days ago I decided to learn why Ramanujan's theory 1+2+3+4+... = -1/12 is the way it is. The first step in the proof/derivation was to consider Grandi's series A = (1-1+1-1+1-1+1-1...) ... user avatar Glace
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-1 votes 1 answer 89 views

How $\phi(2)$ comes into the picture?

We know Ramanujan's $$\phi(a,n) = 1+ 2\sum_{k =0}^{n}{\frac{1}{(ak)^3-ak}}$$ How can I prove $$\sum_{k=1}^n\frac{1}{n+k} = \frac{n}{2n+1} + \sum_{k=1}^n(\frac{1}{(2k)^3-2k})$$ Don't know how to prove ... user avatar Namratha Reddy
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6 votes 2 answers 350 views

Why/How was Hardy impressed with Ramanujan’s work prior to seeing any proofs of their validity?

Hardy’s famous correspondence with Ramanujan highlights an interesting aspect of the mathematics discipline; the appreciation of a mathematical expression prior to knowing its validity. Why/how was ... user avatar Cybernetic
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10 votes 1 answer 156 views

A dig at Ramanujan's: $\sum_{k=1}^{\infty} (-1)^{k-1} \frac{x^{pk}}{k(k!)^p} \sim p \ln x +p \gamma,~ p>0$

Ramanujan's claim on page 98, in the book (`Ramanujan's note book part 1' by Bruce C. Berndt) is that $$\sum_{k=1}^{\infty} (-1)^{k-1} \frac{x^{pk}}{k(k!)^p} \sim p \ln x +p \gamma,\qquad p>0\tag{1}... user avatar Z Ahmed
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3 votes 1 answer 161 views

Ramanujan summation of alternating factorials: why is it $0.596...$?

I was reading Ramanujan's letter to Hardy and came across this identity: $$0!-1!+2!-3!+...=0.596...$$ Ramanujan didn't give the exact value of that constant, but it is the Euler-Gompertz constant, as ... user avatar russian bot
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1 vote 1 answer 241 views

Interpret "the sum of all natural numbers equal $-1/12$" without complex analysis skills

is it possible to show if there is a link between the sum of all natural numbers and the value $ - \frac {1} {12} $, through simple real analysis intuitions? In some contexts of physics this result ... user avatar Patrick Danzi
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5 votes 3 answers 183 views

Computing Ramanujan asymptotic formula from Rademacher's formula for the partition function

I am trying to derive the Hardy-Ramanujan asymptotic formula $$p(n) \sim \frac{1}{4n\sqrt{3}}e^{\pi\sqrt{\frac{2n}{3}}}$$ from Radmacher's formula for the partition function $p(n)$ given by $$p(n)=\... user avatar AgathangelosServias
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6 votes 2 answers 237 views

What is the Ramanujan summation for the series $\sqrt[n]{2}$

A Ramanujan summation is a technique invented by the mathematician Srinivasa Ramanujan for assigning a value to divergent infinite series In my case, I'm interested in assigning a value to the ... user avatar Graviton
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9 votes 3 answers 488 views

Proving $\int_{0}^{1} \frac{\tanh^{-1}\sqrt{x(1-x)}}{\sqrt{x(1-x)}}dx=\frac{1}{3}(8C-\pi\ln(2+\sqrt{3}))$ for an identity of Srinivasa Ramanujan

Ramanujan is supposed to have given more than five thousand elegant results, a good number of them are yet to be proved or disproved. Yesterday in the comment section of Proving that $ \sum_{k=0}^\... user avatar Z Ahmed
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3 votes 1 answer 125 views

Find $\sum_{n=1}^{\infty} \frac{n^{\sigma -1} (n+\sigma )-(n+1)^{\sigma }}{\sigma(1-\sigma)}$ for $ 0<\sigma<1$

Find $\sum_{n=1}^{\infty} \frac{n^{\sigma -1} (n+\sigma )-(n+1)^{\sigma }}{\sigma(1-\sigma)}$ for $ 0<\sigma<1$ My try $ \sum_{n=1}^{\infty} \frac{n^{\sigma -1} (n+\sigma )-(n+1)^{\sigma }}{\... user avatar user768142 4 votes 2 answers 198 views

Found this identity by accident

I found the following identity when trying to prove something else: $$\sum\limits_{n=1}^\infty\frac{(n-1)!x}{\prod\limits_{k=1}^n (k+x)}\equiv 1,~ \forall x>0$$ I'm sure there's a name for it (or ... user avatar user64735
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-1 votes 1 answer 244 views

Can the ramanujan summation formula be used to evaluate convergent series?

I know it's used to give values to divergent series, but when applied to absolutely convergent series, does it give the value at which the series converges? By the way since someone asked about how I ... user avatar Perch
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-2 votes 2 answers 284 views

Ramanujan Summation's -1/12 is not an element of the group of all positive integers. Does this prove the summation wrong? [duplicate]

Ramanujan's Summation says that the sum of all integers is -1/12... 1 + 2 + 3...=-1/12. If we define group G to be group of all positive integers, then the group contains all positive integers. Since ... user avatar Prefix-1
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0 votes 0 answers 177 views

What is Landau Ramanujan constant?

What is Landau Ramanujan constant? I searched on Wikipedia but explanation was not clear enough please explain it along with example thank you user avatar PRATEEK MOURYA
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