A034095 Indices of (-1)sigma perfect numbers.

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

Offset: 1

Author

Yasutoshi Kohmoto

Keywords

• nonn
• more

Crossrefs

Cf. A034094, A049060.

Programs

Mathematica

f[p_, e_] := (p^(e+1)-2*p+1)/(p-1); r[1] = 1; r[n_] := (Times @@ f @@@ FactorInteger[n])/n; Select[r /@ Range[10^5], IntegerQ] (* Amiram Eldar, Jul 07 2022 *)

Formula

a(n) = (-1)sigma(A034094(n))/A034094(n) where (-1)sigma(n) = A049060(n).

Extensions

a(1)=1 prepended and offset corrected by Michel Marcus, Jun 02 2016

a(10) and a(11) switched and missing term a(13) inserted by Amiram Eldar, Jul 07 2022