1065070domain: NAppears in sequencesNumber of chiral n-ominoes in n-1 space.at n=23A0456493^(n-1)*(2*3^(n-1)+3)+1.at n=6A169723Triangular numbers k such that phi(k) is a square number, where phi(k) is the Euler totient function (A000010).at n=28A287473