login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A126016 Numbers whose aliquot sequence does not terminate in 1. 5
6, 25, 28, 95, 119, 143, 220 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sequence continues 276?, 284, 306?, 396?, 417, 445, 496, .... Because 276,306 and 396 are all in the same family, either all 3 are present or none are. It is not known whether any aliquot sequence grows without bound; 276 is the smallest number for which this is unknown.

Additional tentative terms: 552, 562, 564, 565, 608, 650, 652, 660, 675, 685, 696, 780, 783, 790, 828, 840, 888, 909, 913, 966, 996, 1064, 1074, 1086, 1098, ... - Jean-Fran├žois Alcover, Nov 14 2013

LINKS

Table of n, a(n) for n=1..7.

Eric Weisstein's World of Mathematics, Aliquot Sequence

P. Zimmermann, Latest information

MATHEMATICA

maxAliquot = 10^45; A131884 = {}; s[1] = 1; s[n_] := DivisorSigma[1, n] - n; selQ[n_ /; n <= 5] = True; selQ[n_] := NestWhile[s, n, If[{##}[[-1]] > maxAliquot, Print["A131884: ", n]; AppendTo[A131884, n]; False, Length[{##}] < 4 || {##}[[-4 ;; -3]] != {##}[[-2 ;; -1]]] & , All] == 1; Reap[For[k = 1, k < 1100, k++, If[!selQ[k], Print[k]; Sow[k]]]][[2, 1]]

CROSSREFS

Complement of A080907. Includes A000396, A063990 and other sociable numbers, A063769, numbers whose aliquot sequence reaches a sociable number and numbers whose aliquot sequence grows without bound.

Sequence in context: A184388 A136606 A074096 * A237286 A046416 A042879

Adjacent sequences:  A126013 A126014 A126015 * A126017 A126018 A126019

KEYWORD

hard,nonn

AUTHOR

Franklin T. Adams-Watters, Dec 14 2006

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 22 08:57 EST 2017. Contains 295076 sequences.