A143721 Aliquot sequence starting at 38.

38, 22, 14, 10, 8, 7, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

0,1

Comments

From Michal Paulovic, Dec 31 2017: (Start)

The only integer with the sum of its proper divisors equal to 38 is 1369.

The sequence's pattern: 6+2^5, 6+2^4, 6+2^3, 6+2^2, 6+2^1, 6+2^0, 1, 0, 0, 0, ...

(End)

Part of the larger aliquot sequence: 12135617199, 5556030801, 2107460079, 1016939121, 496646799, 231221769, 85406391, 55582041, 19742503, 1794785, 366535, 107225, 25765, 5159, 1369, 38, 22, 14, 10, 8, 7, 1, 0, ..., . - Robert G. Wilson v, Mar 05 2018

Links

Table of n, a(n) for n=0..102.

Eric Weisstein's MathWorld, Aliquot Sequence

Formula

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

From Iain Fox, Dec 31 2017: (Start)

G.f.: 38 + 22*x + 14*x^2 + 10*x^3 + 8*x^4 + 7*x^5 + x^6.

E.g.f.: (27360 + 15840*x + 5040*x^2 + 1200*x^3 + 240*x^4 + 42*x^5 + x^6)/720.

(End)

Mathematica

NestList[If[# == 0, 0, DivisorSigma[1, #] - #] &, 38, 100] (* Michael De Vlieger, Dec 31 2017 *)

Prog

(PARI) x=1369; while(x, x=sigma(x)-x; if(x, print1(x ", "), print1(x ", " x ", " x ", ..."))) \\ Michal Paulovic, Dec 31 2017

Crossrefs

Sequence in context: A160147 A033358 A033974 * A333850 A070725 A249280

Adjacent sequences: A143718 A143719 A143720 * A143722 A143723 A143724

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 30 2008

Status

approved