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A permutation with repetition of k elements from set of n elements is ordered sequence of k elements from this set. The elements can repeat. The number of these permutations is given by formula n_PR_k = n⋅n⋅n⋅...⋅n = n^k. Examples. Permutations with repetition of 3 elements from set of 2 elements a, b: aaa, aab, aba, abb, baa, bab, bba, bbb. 2_PR_3 = 2^3 = 8. Permutations with repetition of 2 elements from set of 3 elements a, b, c: aa, ab, ac, ba, bb, bc, ca, cb, cc. 3_PR_2 = 3^2 = 9.