A077089 Quotients when sigma(k+1)/sigma(k) is an integer.

3, 2, 1, 2, 1, 1, 2, 1, 1, 1, 2, 3, 1, 3, 1, 2, 1, 2, 2, 3, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 2, 2, 2, 2, 3, 1, 2, 2, 3, 2, 2, 1, 2, 1, 2, 1, 1, 1, 1, 2, 3, 2, 2, 1, 2, 2, 1, 2, 3, 3, 1, 3, 1, 2, 2, 2, 3, 2, 1, 1, 3, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 1, 3, 3, 2, 1, 2, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1

Offset

1,1

Links

Seiichi Manyama, Table of n, a(n) for n = 1..500

Formula

a(n) = sigma(A058072(n)+1)/sigma(A058072(n)). - Seiichi Manyama, Jan 16 2021

Example

a(1) = sigma(2)/sigma(1) = 3/1 = 3.
a(2) = sigma(6)/sigma(5) = 12/6 = 2.
a(3) = sigma(15)/sigma(14) = 24/24 = 1.

Mathematica

Do[s=Mod[a=DivisorSigma[1, n+1], b=DivisorSigma[1, n]]; If[Equal[s, 0], Print[a/b]], {n, 1, 10000000}]
Select[#[[2]]/#[[1]]&/@Partition[DivisorSigma[1, Range[10^6]], 2, 1], IntegerQ] (* Harvey P. Dale, Dec 26 2015 *)

Crossrefs

Cf. A000203, A002961, A058072, A067081, A077086, A077087.

Sequence in context: A306287 A016457 A181715 * A156352 A175191 A328928

Adjacent sequences: A077086 A077087 A077088 * A077090 A077091 A077092

Keyword

nonn,changed

Author

Labos Elemer, Oct 31 2002

Status

approved