Let P(n):2n>n,∀n∈N and 2k>k,∀n=k, then which of the following is true ∀k≥2?
If Dk=∣∣ ∣ ∣∣1nn2kn2+n+1n2+n2k−1n2n2+n+1∣∣ ∣ ∣∣ and n∑k=1Dk=56, where n∈N, then n is equal to