7635468288domain: NAppears in sequencesLet sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,8)-perfect numbers.at n=19A019285Residue C(2^n,n) mod C(2^n,2).at n=17A060430