33624064domain: NAppears in sequencesNumbers k whose deficiency is 18: sigma(k) - 2*k = -18.at n=4A223608Numbers a(n) = 2^(n-1) * f(n), where n >= 1 and f(n) is the smallest prime number larger than 2^n (A014210).at n=12A246956Numbers k such that sigma(k) == 0 (mod k-9).at n=11A274564