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

1,6

Links

Table of n, a(n) for n=1..18.

Formula

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

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 *)

Crossrefs

Cf. A034094, A049060.

Sequence in context: A297828 A062245 A062246 * A037811 A091237 A143477

Adjacent sequences: A034092 A034093 A034094 * A034096 A034097 A034098

Keyword

nonn,more

Author

Yasutoshi Kohmoto

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

Status

approved