login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181311 Highly abundant numbers k whose largest prime factor is less than log(k). 2
8, 16, 24, 36, 48, 72, 96, 108, 144, 180, 216, 240, 288, 300, 360, 480, 540, 600, 720, 960, 1080, 1200, 1260, 1440, 1620, 1680, 1800, 1920, 2100, 2160, 2400, 2520, 2880, 3024, 3240, 3360, 3600, 3780, 4200, 4320, 5040, 5760, 5880, 6300, 6720, 7200, 7560 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Every highly abundant number (A002093) is either in this sequence or A181312. Although it appears that for every n there is at least one prime p such that n*p is another highly abundant number, this conjecture fails for 46846800, the 227th term.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..4292

MATHEMATICA

seq = {}; sm = 0; Do[s = DivisorSigma[1, n]; If[s > sm, sm = s; If[FactorInteger[n][[-1, 1]] < Log[n], AppendTo[seq, n]]], {n, 1, 8000}]; seq (* Amiram Eldar, Jan 14 2022 *)

CROSSREFS

Cf. A002093, A181312.

Sequence in context: A072066 A342018 A055065 * A083496 A125991 A028589

Adjacent sequences:  A181308 A181309 A181310 * A181312 A181313 A181314

KEYWORD

nonn

AUTHOR

T. D. Noe, Oct 13 2010

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 03:28 EDT 2022. Contains 354110 sequences. (Running on oeis4.)