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A008887 Aliquot sequence starting at 60. 1
60, 108, 172, 136, 134, 70, 74, 40, 50, 43, 1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

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

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, B6.

LINKS

Table of n, a(n) for n=0..11.

Christophe CLAVIER, Aliquot Sequences

Index entries for sequences related to aliquot parts.

FORMULA

a(n+1) = A001065(a(n)). - R. J. Mathar, Oct 11 2017

MAPLE

f := proc(n) option remember; if n = 0 then 60; else sigma(f(n-1))-f(n-1); fi; end:

MATHEMATICA

NestList[If[#==0, 0, DivisorSigma[1, #]-#]&, 60, 80] (* Harvey P. Dale, Nov 29 2013 *)

PROG

(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

CROSSREFS

Cf. A008885 (starting at 30), ..., A008892 (starting at 276), A098007 (length of aliquot sequences).

Sequence in context: A039398 A044001 A258700 * A217738 A182683 A174601

Adjacent sequences:  A008884 A008885 A008886 * A008888 A008889 A008890

KEYWORD

nonn,fini,full

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Edited by M. F. Hasler, Feb 24 2018

STATUS

approved

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Last modified November 11 18:50 EST 2019. Contains 329031 sequences. (Running on oeis4.)