Rewrite. k(kn)1=n!(k−1)!(n−k)!=n1⋅(n−1)!(k−1)!(n−k)!=n1⋅(k−1n−1)1.
Sum. ∑k=1nk(kn)1=n1∑j=0n−1(jn−1)1.
Known identity. ∑j=0n−1(jn−1)1=2n+1n+1∑k=0nk+12k... this depends on the exact sum.
For small n: n=1: 1. n=2: 1/1+1/2=3/2. n=3: 1+1/3+1/3=5/3.
Pattern suggests ∑=nn+1⋅Hn? Try n=2: 3/2=3/2⋅H2=3/2⋅3/2=9/4. No.
Known result. ∑k=1nk(kn)1=2n+1n+1∑k=0nk+12k.
Conclusion. The exact value involves a sum with 2k/(k+1) terms.