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Dec
16
comment Infinite Series $\sum_{n=1}^\infty\frac{H_{2n+1}}{n^2}$
+1. For a different evaluation of $S(-1)$ that relies solely on manipulation of the summation, see robjohn's answer here.
Dec
16
revised The $n^{th}$ root of the geometric mean of binomial coefficients.
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Dec
15
awarded  Necromancer
Dec
3
revised Number of elements of $3n$ binary tuples, where the ordinates add up to $2n$.
fixed grammar
Dec
3
answered Number of elements of $3n$ binary tuples, where the ordinates add up to $2n$.
Nov
26
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Nov
26
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Nov
20
awarded  Popular Question
Nov
19
comment Why is $1^{\infty}$ considered to be an indeterminate form
@Mehrdad: You should ask that as a question on the main site.
Nov
15
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Nov
12
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Nov
7
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Oct
30
comment A recurrence relation for Stirling numbers (2nd kind)
I asked a question about the same sum here. There are lots of different results about this sum in the question and answers there.
Oct
18
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Oct
7
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Oct
7
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Oct
2
comment How this operation is called?
I wrote a paper a few years ago that uses finite differences to evaluate binomial sums. Since the finite difference is $S(a_n) - a_n$, some of the ideas in there are related to your observation here. In case you're interested, the paper is here.
Oct
2
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29
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Sep
26
awarded  Nice Answer