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 A325311 #14 Apr 05 2024 04:43:42 %S A325311 11025,99225,245025,540225,893025,1334025,2205225,3980025,4862025, %T A325311 5832225,6890625,8037225,8555625,9828225,10595025,10989225,12006225, %U A325311 14402025,19847025,20385225,24354225,26163225,26471025,29648025,31979025,35820225,38378025,43758225,46580625,49491225,50339025,52490025,55577025,57836025,60140025 %N A325311 Odd abundant numbers k for which sigma(k) == 3 (mod 4). %C A325311 These are all squares. Square roots are in A325312. %H A325311 Antti Karttunen, <a href="/A325311/b325311.txt">Table of n, a(n) for n = 1..10000</a> %H A325311 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>. %F A325311 a(n) = A325312(n)^2. - _Amiram Eldar_, Apr 05 2024 %t A325311 Select[Range[1, 7755, 2]^2, Mod[(s = DivisorSigma[1, #]), 4] == 3 && s > 2*# &] (* _Amiram Eldar_, Apr 05 2024 *) %o A325311 (PARI) isA325311(n) = (n%2 && (3==sigma(n)%4) && sigma(n)>(2*n)); %Y A325311 Cf. A000203, A324647, A325312 (square roots). %Y A325311 Intersection of A005231 and A324899. %Y A325311 Subsequence of A156942. %K A325311 nonn %O A325311 1,1 %A A325311 _Antti Karttunen_, Apr 20 2019