A054862 (+2)-unitary sigma 3-multiple perfect number: numbers k such that (+2)usigma(k) = 3*k, where (+2)usigma(k) = A107759(k).

105, 45045, 237405, 101846745, 121486365, 274680671265

Offset

1,1

Links

Table of n, a(n) for n=1..6.

Example

(+2)usigma(12) = (2+4)*(2+3) = 30.
Factorizations: 3*5*7, 3^2*5*7*11*13, 3*5*7^2*17*19, 3^2*5*7^2*11*13*17*19, 3^3*5*7*11*13*29*31, 3^3*5*7^2*11*13*17*19*29*31.

Mathematica

s[n_] := Times @@ (2 + Power @@@ FactorInteger[n]); s[1] = 1; Select[Range[2.5*10^5], s[#] == 3*# &] (* Amiram Eldar, Aug 26 2022 *)

Crossrefs

Cf. A052396, A107759.

Sequence in context: A145621 A167779 A275461 * A348794 A028917 A145627

Adjacent sequences: A054859 A054860 A054861 * A054863 A054864 A054865

Keyword

nonn,more

Author

Yasutoshi Kohmoto

Extensions

Offset corrected by Amiram Eldar, Aug 26 2022

Status

approved