This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A034095 #15 Jul 07 2022 08:11:41 %S A034095 1,1,1,1,1,2,2,2,1,1,2,1,2,2,2,2,2,3 %N A034095 Indices of (-1)sigma perfect numbers. %F A034095 a(n) = (-1)sigma(A034094(n))/A034094(n) where (-1)sigma(n) = A049060(n). %t A034095 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 A034095 Cf. A034094, A049060. %K A034095 nonn,more %O A034095 1,6 %A A034095 _Yasutoshi Kohmoto_ %E A034095 a(1)=1 prepended and offset corrected by _Michel Marcus_, Jun 02 2016 %E A034095 a(10) and a(11) switched and missing term a(13) inserted by _Amiram Eldar_, Jul 07 2022