cp's OEIS Frontend

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.

A332478 Number that are unitary norm-multiply-perfect numbers in Gaussian integers.

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%I A332478 #4 Feb 13 2020 20:15:37
%S A332478 1,10,12,20160,15713280,137592000,44289146880
%N A332478 Number that are unitary norm-multiply-perfect numbers in Gaussian integers.
%C A332478 Numbers k such that their norm of sum of unitary divisors in Gaussian integers, A332474(k), is divisible by their norm, k^2.
%C A332478 The corresponding ratios A332474(a(n))/(a(n)^2) are 1, 4, 1, 5, 5, 2, 5.
%e A332478 10 is a term since its sum of unitary divisors in Gaussian integers is -12 + 16*i, whose norm (-12)^2 + 16^2 = 400 is divisible by 10^2 = 100.
%t A332478 f[p_, e_] := If[Abs[p] == 1, 1, (p^e + 1)]; Select[Range[21000], Divisible[Abs[ Times @@ f @@@ FactorInteger[#, GaussianIntegers -> True]]^2, #^2] &]
%Y A332478 Cf. A002827, A327158, A332318, A332319, A332474.
%K A332478 nonn,more
%O A332478 1,2
%A A332478 _Amiram Eldar_, Feb 13 2020