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!)
A140522 Numbers for which sigma(n) - 2n exceeds sigma(k) - 2k for all k < n. 3

%I

%S 1,6,12,24,36,48,60,72,84,96,108,120,168,180,240,300,336,360,420,480,

%T 540,600,660,720,840,1008,1080,1200,1260,1440,1680,2100,2160,2520,

%U 3240,3360,3780,3960,4200,4620,4680,5040,6300,6720,7200,7560,8400,9240,10080

%N Numbers for which sigma(n) - 2n exceeds sigma(k) - 2k for all k < n.

%H Donovan Johnson, <a href="/A140522/b140522.txt">Table of n, a(n) for n = 1..500</a>

%e 72 is the smallest number > 60 with an abundance > the abundance of 60. - _Donovan Johnson_, Jan 20 2012

%t a = {1}; m = -1; For[n = 2, n < 20000, n++, If[DivisorSigma[1, n] - 2*n > m, m = DivisorSigma[1, n] - 2*n; AppendTo[a, n]]]; a (* _Stefan Steinerberger_, Aug 04 2008 *)

%Y Cf. A002093 (d=0) and A034090 (d=1).

%K nonn

%O 1,2

%A _J. Lowell_, Jul 02 2008

%E More terms from _Stefan Steinerberger_, Aug 04 2008

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 September 24 11:11 EDT 2020. Contains 337317 sequences. (Running on oeis4.)