A045477 Aliquot sequence starting at 840 (reaches 1 at 747th term).

840, 2040, 4440, 9240, 25320, 51000, 117480, 271320, 765480, 1531320, 3721800, 7817640, 15635640, 32899560, 65799480, 139098120, 349027320, 699333000, 1597611000, 3386944680, 9543610200, 20041583280

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full

References

• A. W. P. Guy and R. K. Guy, A record aliquot sequence, pp. 557-559 of Mathematics of Computation 1943-1993 (Vancouver, 1993), Proc. Symp. Appl. Math., Vol. 48, Amer. Math. Soc. 1994.

Links

• T. D. Noe, Table of n, a(n) for n = 0..748
• Christophe CLAVIER, Aliquot Sequences

Programs

Mathematica

FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 840] // Most (* Jean-François Alcover, Mar 28 2020 *)

Formula

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