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.

A332532 Even numbers k such that the sum of divisors of k in Gaussian integers is a real number.

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%I A332532 #8 Feb 16 2020 02:43:44
%S A332532 10250,30750,40400,71750,92250,112750,121200,194750,215250,235750,
%T A332532 276750,282800,308050,317750,338250,363600,440750,444400,467860,
%U A332532 481750,502250,584250,604750,645750,686750,707250,727750,767600,789250,809750,830250,848400,850750
%N A332532 Even numbers k such that the sum of divisors of k in Gaussian integers is a real number.
%C A332532 Even numbers k such that A103229(k) = 0.
%C A332532 The odd numbers with this property are the numbers that are divisible only by primes congruent to 3 mod 4 (A004614).
%H A332532 Amiram Eldar, <a href="/A332532/b332532.txt">Table of n, a(n) for n = 1..10000</a>
%e A332532 10250 is a term since its sum of divisors in Gaussian integers is 41600 which is a real number.
%t A332532 Select[Range[2, 10^6, 2], Im[DivisorSigma[1, #, GaussianIntegers -> True]] == 0 &]
%Y A332532 Subsequence of A332531.
%Y A332532 Cf. A004614, A103228, A103229.
%K A332532 nonn
%O A332532 1,1
%A A332532 _Amiram Eldar_, Feb 15 2020