`((n+k-1),(k)) = ( ( n + k -1)! ) / ( k !( n - 1)! )`

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The Repeat Combinations calculator computes the number of combination possible in a set of k elements with possible repetitions from a finite set of n objects where order does not matter. 

INSTRUCTIONS: Enter the following:

• (n) The total number of objects.
• (k) The number of objects in the subset 

Combinations with Repititions: The calculator computes and return the number of combinations C_r(n,k).

The Math

The formula for combinations with repetitions is as follows:

                    C_r(n, k) = ` ((n+k-1)!)/(k!(n-1)!)`

Combinatorics Calculators

• n! - factorial
• `n!  sqrt(2 pi n) (n/e)^n ` - Stirling's factorial approximation
• _nC_k - combinations
• C_r(n,k) - combinations with repetitions
• _nP_k - permutations
• P_r(n) - permutations with repetitions
• P_comp(n,2) - Comparison permutations
• P_c(n,r) - Circular Permutation