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A034095
Indices of (-1)sigma perfect numbers.
1
1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 2, 3
OFFSET
1,6
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
Sequence in context: A297828 A062245 A062246 * A037811 A091237 A143477
KEYWORD
nonn,more
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