Numbers n such that lcm(sigma(n), n) = tau(n) * sigma(n) where sigma(k) = the sum of the divisors of k (A000203) and tau(k) = the number of divisors of k (A000005).

A306655

Numbers n such that lcm(sigma(n), n) = tau(n) * sigma(n) where sigma(k) = the sum of the divisors of k (A000203) and tau(k) = the number of divisors of k (A000005).

Terms

    a(0) =1a(1) =2a(2) =18a(3) =468a(4) =9360a(5) =10880a(6) =79360a(7) =84480a(8) =387072a(9) =777216a(10) =3801600a(11) =7282688a(12) =15037440a(13) =17418240a(14) =27067392a(15) =65544192a(16) =752903424a(17) =1218032640a(18) =4227842304a(19) =4737761280a(20) =6410638080a(21) =11949932544a(22) =19327057920a(23) =26372530800a(24) =37645171200a(25) =224956569600a(26) =243520929792a(27) =876611248128

External references