315957domain: NAppears in sequencesa(n) = Sum_{i=1..n, j=1..n, gcd(i,j)=1} (n+1-i)*(n+1-j).at n=36A115004Numerators of Harary index for the n-Mycielski graph.at n=9A296193a(n) = A115004(2n+1).at n=18A331759