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%I #15 Jul 07 2022 08:11:41
%S 1,1,1,1,1,2,2,2,1,1,2,1,2,2,2,2,2,3
%N Indices of (-1)sigma perfect numbers.
%F a(n) = (-1)sigma(A034094(n))/A034094(n) where (-1)sigma(n) = A049060(n).
%t 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 *)
%Y Cf. A034094, A049060.
%K nonn,more
%O 1,6
%A _Yasutoshi Kohmoto_
%E a(1)=1 prepended and offset corrected by _Michel Marcus_, Jun 02 2016
%E a(10) and a(11) switched and missing term a(13) inserted by _Amiram Eldar_, Jul 07 2022
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