login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A292983 Bi-unitary highly abundant numbers: numbers n such that bsigma(n) > bsigma(m) for all m < n, where bsigma is the sum of the bi-unitary divisors function (A188999). 4
1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 21, 22, 24, 30, 40, 42, 48, 54, 66, 72, 78, 88, 96, 120, 160, 168, 210, 216, 240, 264, 312, 330, 360, 378, 384, 408, 456, 480, 600, 648, 672, 840, 1056, 1080, 1320, 1512, 1560, 1680, 1848, 1920, 2040, 2184, 2280, 2640 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Analogous to highly abundant numbers (A002093) with bi-unitary sigma (A188999) instead of sigma (A000203).

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..569 (terms below 10^10)

MATHEMATICA

f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bsigma[m_] := DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; a = {}; bmax = 0; Do[b = bsigma[n]; If[b > bmax, AppendTo[a, n]; bmax = b], {n, 3000}]; a (* after Michael De Vlieger at A188999 *)

CROSSREFS

Cf. A002093, A188999, A285614.

Sequence in context: A120370 A011866 A321152 * A174709 A008724 A287642

Adjacent sequences:  A292980 A292981 A292982 * A292984 A292985 A292986

KEYWORD

nonn

AUTHOR

Amiram Eldar, Sep 27 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 12 09:39 EDT 2021. Contains 342920 sequences. (Running on oeis4.)