A008889 Aliquot sequence starting at 150.

150, 222, 234, 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, 2109796, 1889486, 953914, 668966, 353578, 176792

Offset

0,1

Comments

Start at 150, and repeatedly apply the map x -> Sum of divisors of x excluding x.

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

References

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

Links

Ivan Panchenko, Table of n, a(n) for n = 0..177 (full sequence).

Christophe CLAVIER, Aliquot Sequences

Factordb, Whole sequence starting with 150

Index entries for sequences related to aliquot parts.

Formula

a(n) = A008888(n+1). - R. J. Mathar, Oct 28 2008

Maple

f := proc(n) option remember; if n = 0 then 150; else sigma(f(n-1))-f(n-1); fi; end:

Mathematica

FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 150] // Most (* Jean-François Alcover, Mar 28 2020 *)

Prog

(PARI) a(n, a=150)={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: A048706 A054729 A116185 * A184075 A207044 A292705

Adjacent sequences: A008886 A008887 A008888 * A008890 A008891 A008892

Keyword

nonn,fini,full

Author

N. J. A. Sloane

Status

approved