A008890 - OEIS

A008890

Aliquot sequence starting at 168.

168, 312, 528, 960, 2088, 3762, 5598, 6570, 10746, 13254, 13830, 19434, 20886, 21606, 25098, 26742, 26754, 40446, 63234, 77406, 110754, 171486, 253458, 295740, 647748, 1077612, 1467588, 1956812

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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 175. - M. F. Hasler, Feb 24 2018

REFERENCES

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

LINKS

T. D. Noe, Table of n, a(n) for n = 0..175 (a(176) removed by Georg Fischer, Apr 28 2019)

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 168; else sigma(f(n-1))-f(n-1); fi; end:

MATHEMATICA

NestList[DivisorSigma[1, #] - # &, 168, 175] (* Alonso del Arte, Feb 24 2018 *)

PROG

(PARI) a(n, a=168)={for(i=1, n, a=sigma(a)-a); a} \\ M. F. Hasler, Feb 24 2018

CROSSREFS

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

Sequence in context: A059463 A302365 A038812 * A230479 A105915 A158219

Adjacent sequences: A008887 A008888 A008889 * A008891 A008892 A008893

KEYWORD

nonn,fini,full

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Edited by M. F. Hasler, Feb 24 2018

STATUS

approved