A302572 Unitary barely deficient numbers: unitary deficient numbers k such that usigma(k)/k > usigma(m)/m for all unitary deficient numbers m < k, where usigma(k) is the sum of the unitary divisors of k (A034448).

1, 2, 10, 84, 110, 1155, 6490, 34320, 55335, 80652, 163212, 449295, 676390, 1360810, 1503370, 1788490, 3214090, 22627605, 32062485, 35604492, 103712410, 365690892, 615206030, 815634435

Offset

1,2

Links

Table of n, a(n) for n=1..24.

Example

The values of usigma(k)/k are 1, 1.5, 1.8, 1.904..., 1.963..., 1.994...

Mathematica

usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; seq = {}; r = 0; Do[s = usigma[n]/n; If[s < 2 && s > r, AppendTo[seq, n]; r = s], {n, 1, 1000000}]; seq

Crossrefs

Cf. A034448, A071927, A302570.

Sequence in context: A298690 A101878 A121194 * A121516 A024491 A250117

Adjacent sequences: A302569 A302570 A302571 * A302573 A302574 A302575

Keyword

nonn,more

Author

Amiram Eldar, Apr 10 2018

Status

approved