2384928domain: NAppears in sequencesa(n) = n^2*(n+1)*(n+2)^2/6.at n=26A004256a(n) = n^2*(n^2 - 1)^2/2.at n=12A288959a(n) = phi(3^n-1), where phi is Euler's totient function (A000010).at n=13A295500Detour index for the n X n torus grid graph.at n=10A296784a(n) = phi(9^n-1), where phi is Euler's totient function (A000010).at n=6A366663