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 A125271 #13 Feb 16 2025 08:33:04
%S A125271 1,4,2,7,6,8,2,10,3,20,2,14,6,8,12,13,6,12,2,34,4,8,2,20,15,20,4,14,6,
%T A125271 40,2,16,4,20,12,21,6,8,12,48,6,16,2,14,18,8,2,26,3,48,12,34,6,16,12,
%U A125271 20,4,20,2,68,6,8,6,19,28,16,2,34,4,40,2,30,6,20,30
%N A125271 Number of Gaussian integer divisors of n (having positive real part).
%C A125271 To avoid the redundancy of counting the negatives of the divisors, we consider only divisors having a positive real part.
%C A125271 The usual method of counting complex divisors is to exclude associates. For example, although 1+i and 1-i both divide 2, one is just -i times the other. This sequence counts each first-quadrant complex divisor twice. Sequence A062327 counts those complex divisors only once. - _T. D. Noe_, Feb 21 2007
%H A125271 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GaussianInteger.html">Gaussian Integer</a>.
%F A125271 a(n) = 2*A062327(n) - A000005(n). - _T. D. Noe_, Feb 21 2007
%e A125271 a(5) = 6 because 5 is divisible by the Gaussian integers {1, 1-2i, 1+2i, 2-i, 2+i, 5}, which is 6 divisors in all.
%Y A125271 Cf. A000005, A062327.
%K A125271 easy,nonn
%O A125271 1,2
%A A125271 Mitch Cervinka (puritan(AT)toast.net), Jan 16 2007