2
$\begingroup$

Just to sharpen my intuition in combinatorics, I ask you of ways to think about interesting combinatorical quantities and expressions like the binomial coefficient, for example, for the binomial coefficient I know the following

  • There are $\binom{n}{k}$ ways to choose k elements from a set of n elements
  • There are $\binom{n}{k}$ strings over $\{0,1\}$ with exactly $k$ ones
  • There are $\binom n k$ shortest paths in an rectangular grid from $(0,0)$ to $(k, n-k)$.

Are there more?

$\endgroup$
  • $\begingroup$ There are many, many "combinatorial quantities and expressions like the binomial coefficient," and even more ways to think about them all. $\endgroup$ – anon Jul 17 '12 at 21:05
  • 7
    $\begingroup$ oeis.org/A007318 $\endgroup$ – datageist Jul 17 '12 at 21:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.