This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A008888 #44 Jul 08 2025 01:22:53
%S A008888 138,150,222,234,312,528,960,2088,3762,5598,6570,10746,13254,13830,
%T A008888 19434,20886,21606,25098,26742,26754,40446,63234,77406,110754,171486,
%U A008888 253458,295740,647748,1077612,1467588,1956812,2109796,1889486,953914,668966,353578,176792
%N A008888 Aliquot sequence starting at 138.
%C A008888 The sum-of-divisor function A000203 and aliquot parts A001065 are defined only for positive integers, so the trajectory ends when 0 is reached, here at index 178. - _M. F. Hasler_, Feb 24 2018
%C A008888 Merges into sequence A008889 after the first step.
%D A008888 R. K. Guy, Unsolved Problems in Number Theory, B6.
%D A008888 Enoch Haga, Exploring Prime Numbers on Your PC, 2nd ed., 1998, pages 83-84 and Table 8, page 46. ISBN 1-885794-16-9.
%H A008888 T. D. Noe, <a href="/A008888/b008888.txt">Table of n, a(n) for n = 0..178</a> (full sequence).
%H A008888 Christophe Clavier, <a href="http://christophe.clavier.free.fr/Aliquot/site/Aliquot.html">Aliquot Sequences</a>
%H A008888 Passawan Noppakaew and Prapanpong Pongsriiam, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL26/Pongsriiam/pong43.html">Product of Some Polynomials and Arithmetic Functions</a>, J. Int. Seq. (2023) Vol. 26, Art. 23.9.1.
%H A008888 <a href="/index/Al#ALIQUOT">Index entries for sequences related to aliquot parts</a>.
%F A008888 a(n) = A001065(a(n-1)) for n > 0, thus a(n) = A001065^n(138) for all n < 179. - _M. F. Hasler_, Nov 16 2013
%F A008888 a(n) = A008889(n-1) for all n >= 1. - _M. F. Hasler_, Feb 24 2018
%p A008888 f := proc(n) option remember; if n = 0 then 138; else sigma(f(n-1))-f(n-1); fi; end:
%t A008888 FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 138] // Most (* _Jean-François Alcover_, Mar 28 2020 *)
%o A008888 (PARI) a(n,a=138)={for(i=1,n,a=sigma(a)-a);a} \\ _M. F. Hasler_, Feb 24 2018
%Y A008888 Cf. A008885 (starting at 30), ..., A008892 (starting at 276), A098007 (length of aliquot sequences).
%K A008888 nonn,fini,full
%O A008888 0,1
%A A008888 _N. J. A. Sloane_
%E A008888 Term 179 removed from b-file by _Ivan Panchenko_, Nov 16 2013
%E A008888 Edited by _M. F. Hasler_, Feb 24 2018