1588491domain: NAppears in sequencesNear 2-hyperperfect numbers: numbers k such that sigma(k) - 3*k/2 - 1/2 is a proper divisor of k.at n=35A305616a(n) is the least nonnegative integer k such that the 2-valuation of 3^k+5 is n, or -1 if no such number exists.at n=21A368350