%I #46 Mar 28 2020 07:59:23
%S 150,222,234,312,528,960,2088,3762,5598,6570,10746,13254,13830,19434,
%T 20886,21606,25098,26742,26754,40446,63234,77406,110754,171486,253458,
%U 295740,647748,1077612,1467588,1956812,2109796,1889486,953914,668966,353578,176792
%N Aliquot sequence starting at 150.
%C Start at 150, and repeatedly apply the map x -> Sum of divisors of x excluding x.
%C 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 14. - _M. F. Hasler_, Feb 24 2018
%D R. K. Guy, Unsolved Problems in Number Theory, B6.
%H Ivan Panchenko, <a href="/A008889/b008889.txt">Table of n, a(n) for n = 0..177</a> (full sequence).
%H Christophe CLAVIER, <a href="http://christophe.clavier.free.fr/Aliquot/site/Aliquot.html">Aliquot Sequences</a>
%H Factordb, <a href="http://www.factordb.com/sequences.php?se=1&aq=150&action=all&fr=0&to=100">Whole sequence starting with 150</a>
%H <a href="/index/Al#ALIQUOT">Index entries for sequences related to aliquot parts</a>.
%F a(n) = A008888(n+1). - _R. J. Mathar_, Oct 28 2008
%p f := proc(n) option remember; if n = 0 then 150; else sigma(f(n-1))-f(n-1); fi; end:
%t FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 150] // Most (* _Jean-François Alcover_, Mar 28 2020 *)
%o (PARI) a(n,a=150)={for(i=1,n,a=sigma(a)-a);a} \\ _M. F. Hasler_, Feb 24 2018
%Y Cf. A008885 (starting at 30), ..., A008892 (starting at 276), A098007 (length of aliquot sequences).
%K nonn,fini,full
%O 0,1
%A _N. J. A. Sloane_