Below is the particular expression I am concerned with.
I suppose it denotes some sort of operation but I am unsure as to what. I'd appreciate some guidance. Thanks.
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2That notation almost always refers to the Binomial Coefficients – lulu Mar 26 '16 at 00:07
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Looks like a binomial coefficient. – Christopher Carl Heckman Mar 26 '16 at 00:07
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It's another symbol for "combinations" – Ben Grossmann Mar 26 '16 at 00:54
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It is the Binomial coefficient $$ \binom w i = \frac{w!}{i!(w-i)!} $$ Or $$ \binom w i = \frac{w^{\underline i}}{i!} $$ where $w^{\underline i} = w(w-1)\dots(w-i+1)$ is the falling factorial.
Henricus V.
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It's almost always a binomial coefficient: $$ \binom{n}{k} $$ (often pronounced "$n$ choose $k$") denotes the number of ways to choose $k$ elements from a set of $n$ elements.
