[BioC] Distribution Derivation

[E Motakis, Mathematics]

Hi all,

I have the following expression:

P(J=j)= [1/(2^(2N-m))]*[Combination(2N-m; n-i)* Combination(m; i)] / 
Combination(N; n)

It is similar to the hypergeometric distribution but it is not. Can anyone 
tell me whether this is a known distribution (I cannot find anything that 
looks like it).

Can this be written as an H-function or hypergeometric function? (it seems 
to me that it is not, however, any suggestions are appreciated)

Thanks for your help,
Mike

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E Motakis, Mathematics
E.Motakis at bristol.ac.uk