Ok, it's been communicated that using the entropy function would provide a better approximation to nCr. So here is such a formula:
Let H(eps) := eps.log_2(eps)(1eps)log_2(1eps) be a binary entropy function.
Then binom(n, eps.n) is approximately equal to 2^(n.H(eps)).
Where eps is short for epsilon.
Update: Note that this uses the more common Stirling formula which is slightly less accurate as it truncates terms in the series (instead of approximating them like the formula i posted before).
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
 a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

For: 

Use: 
 &   & 
 <   < 
 >   > 
 [   [ 
 ]   ] 
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.

