Pseudocode for view the combinations . Can you help me please with a program which can calculate the number of combinations and to view it ? A pseudocode ? Is there something like a code - to program it ? 
thanks :) 

To compute all the permutations of a set $X$, you operate recursively:


*

*If $X$ is empty, $X=\emptyset$, then the set of permutations is $\{\emptyset\}$.

*If $X$ is not empty, then take each element $x\in X$, and adjoin it to the set of permutations of $X$ without the element $x$.


Writing this in Haskell is a straightforward translation of the above algorithm. First we import a function to let us delete elements from a list:
import Data.List (delete)

then the function that compute all permutations is simply:
perms [] = [[]]
perms xs = [ x : ps | x <- xs, ps <- perms (delete x xs) ]

Checking it works:
> perms "abc"
["abc", "acb", "bac", "bca", "cab", "cba"]

