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 A348584 #6 Oct 24 2021 09:37:53 %S A348584 1,12,56,180,992,16256,127400,441000,2646000,67100672,325458000, %T A348584 2758909440,17179738112,274877382656 %N A348584 Numbers k such that k | A328258(k). %C A348584 The corresponding ratios A113184(k)/k are 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, ... %C A348584 If p is a Mersenne exponent (A000043), then 2^p*(2^p-1) (twice an even perfect number) is a term with ratio A328258(k)/k = -1. %C A348584 If there exists an odd term k, then it is a unitary multiply-perfect number (A327158), since A328258(k) = A034448(k) for an odd k. %e A348584 12 is a term since A328258(12) = -12 is divisible by 12. %t A348584 f[p_, e_] := 1 - (-1)^p*(p^e); s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[3*10^6], Divisible[s[#], #] &] %Y A348584 The unitary version of A348583. %Y A348584 A139256 is a subsequence. %Y A348584 Cf. A000043, A034448, A327158, A328258. %K A348584 nonn,more %O A348584 1,2 %A A348584 _Amiram Eldar_, Oct 24 2021