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%I #17 Feb 24 2018 22:41:03
%S 60,108,172,136,134,70,74,40,50,43,1,0
%N Aliquot sequence starting at 60.
%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 11. - _M. F. Hasler_, Feb 24 2018
%D R. K. Guy, Unsolved Problems in Number Theory, B6.
%H Christophe CLAVIER, <a href="http://christophe.clavier.free.fr/Aliquot/site/Aliquot.html">Aliquot Sequences</a>
%H <a href="/index/Al#ALIQUOT">Index entries for sequences related to aliquot parts</a>.
%F a(n+1) = A001065(a(n)). - _R. J. Mathar_, Oct 11 2017
%p f := proc(n) option remember; if n = 0 then 60; else sigma(f(n-1))-f(n-1); fi; end:
%t NestList[If[#==0,0,DivisorSigma[1,#]-#]&,60,80] (* _Harvey P. Dale_, Nov 29 2013 *)
%o (PARI) a(n,a=60)=for(i=1,n,a=sigma(a)-a);a \\ Will raise an error for n > 11, in agreement with the definition. - _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_.
%E Edited by _M. F. Hasler_, Feb 24 2018
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