A336671 Unitary barely 3-abundant: numbers m such that 3 < usigma(m)/m < usigma(k)/k for all numbers k < m, where usigma is the sum of unitary divisors function (A034448).

30030, 39270, 43890, 46410, 51870, 62790, 67830, 79170, 82110, 91770, 103530, 161070, 166530, 709170, 718410, 723030, 732270, 764610, 778470, 801570, 806190, 815430, 829290, 833910, 847770, 861630, 875490, 884730, 155934030, 264670770, 1234205070, 1448478570

Offset: 1

Author

Amiram Eldar, Jul 29 2020

Keywords

• nonn

Comments

The corresponding values of usigma(m)/m are 3.222..., 3.168...., 3.149..., 3.127..., 3.109..., ...

Links

• Amiram Eldar, Table of n, a(n) for n = 1..36

Crossrefs

The unitary version of A259312.

Subsequence of A285615.

Cf. A034448, A034683, A302570, A336672.

Programs

Mathematica

usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); s = {}; rm = 4; Do[r = usigma[n]/n; If[r > 3 && r < rm, rm = r; AppendTo[s, n]], {n, 1, 10^5}]; s