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

1,1

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..., ...

Links

Table of n, a(n) for n=1..19.

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

Crossrefs

The exponential version of A188263.

The odd version of A336254.

Subsequence of A321147.

Similar sequences: A335052, A335053, A335055.

Cf. A051377.

Sequence in context: A046327 A206044 A321147 * A176364 A283073 A328374

Adjacent sequences: A336676 A336677 A336678 * A336680 A336681 A336682

Keyword

nonn,more

Author

Amiram Eldar, Jul 30 2020

Status

approved