Dirichlet divisor problem my formulas

From _Mats Granvik_, May 28 2017, Apr 05 2020: (Start)

Sum_{k=1..n} A255315(n, k) = n.

a(n) = (n^2-(2*(Sum_{k=1..n} A255315(n,k)*(n-k+1))-n))+2*n-floor(sqrt(n)).

a(n) = -((n^2-(2*(Sum_{k=1..n} A255315(n,n-k+1)*(n-k+1))-n))-2*n+floor(sqrt(n))). (End)