A335053 Odd bi-unitary abundant numbers whose bi-unitary abundancy is closer to 2 than that of any smaller odd bi-unitary abundant number.

945, 25515, 46035, 49875, 83265, 354585, 359205, 361515, 366135, 382305, 389235, 396165, 400785, 403095, 407715, 414645, 416955, 423885, 430815, 437745, 442365, 13351635, 132335385, 159030135, 1756753845, 6561644355, 10394173335, 13455037365, 37456183215

Offset: 1

Author

Amiram Eldar, May 21 2020

Keywords

• nonn

Comments

The bi-unitary abundancy of a number k is bsigma(k)/k, where bsigma(k) is the sum of bi-unitary divisors of k (A188999).

Examples

			The bi-unitary abundancies of the first terms are 2.031..., 2.005..., 2.0019..., 2.0018..., 2.0015..., ...
		

Crossrefs

Cf. A188999, A188263, A293186, A302571, A335052, A335055.

Programs

Mathematica

fun[p_, e_] := If[OddQ[e], (p^(e + 1) - 1)/(p - 1), (p^(e + 1) - 1)/(p - 1) - p^(e/2)]; bsigma[1] = 1; bsigma[n_] := Times @@ (fun @@@ FactorInteger[n]); seq = {}; r = 3; Do[s = bsigma[n]/n; If[s > 2 && s < r, AppendTo[seq, n]; r = s], {n, 1, 10^6, 2}]; seq