A336679 Odd exponential abundant numbers whose exponential abundancy is closer to 2 than that of any smaller odd exponential abundant number.

225450225, 385533225, 481583025, 538472025, 672624225, 985646025, 1150227225, 1566972225, 1685513025, 2105433225, 2679615225, 6485886225, 6554064825, 6933060225, 9150077475, 179678493225, 185601564225, 191620685025, 195686793225

Offset: 1

Author

Amiram Eldar, Jul 30 2020

Keywords

• nonn
• more

Comments

The exponential abundancy of a number k is esigma(k)/k, where esigma(k) is the sum of exponential divisors of k (A051377).

The corresponding values of esigma(k)/k are 2.148..., 2.112..., 2.099..., 2.085..., 2.072..., ...

Crossrefs

The exponential version of A188263.

The odd version of A336254.

Subsequence of A321147.

Similar sequences: A335052, A335053, A335055.

Cf. A051377.

Programs

Mathematica

esigma[n_] := Times @@ (Sum[First[#]^d, {d, Divisors[Last[#]]}] &) /@ FactorInteger[n]; seq = {}; rm = 3; Do[r = esigma[n]/n; If[r > 2 && r < rm, rm = r; AppendTo[seq, n]], {n, 1, 10^9, 2}]; seq