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 A078930 #8 May 10 2013 12:45:08 %S A078930 1,5,4,13,12,20,8,29,13,56,12,52,24,40,48,61,28,65,20,144,32,60,24, %T A078930 116,81,112,40,104,44,224,32,125,48,136,96,169,52,100,96,320,60,160, %U A078930 44,156,156,120,48,244,57,369,112,288,72,200,144,232,80,212,60,576,84,160,104 %N A078930 Let r+i*s be the sum of the distinct first-quadrant Gaussian integers dividing n; sequence gives r+s values. %C A078930 A078910(n)-A078911(n) = A000203(n). %C A078930 Also equal to the sum of all divisors of n (in Z[i]) having positive real part. - _M. F. Hasler_, Nov 22 2007 %H A078930 M. F. Hasler, <a href="/A078930/b078930.txt">Table of n, a(n) for n = 1..1000</a>. %H A078930 Project Euler, <a href="http://projecteuler.net/index.php?section=problems&id=153">Problem 153: Investigating Gaussian Integers</a>. %F A078930 a(n) = A078910(n)+A078911(n). %F A078930 a(n) = A000203(n)+2*A078911(n). - M. F. Hasler, Nov 22 2007 %o A078930 (PARI) A078930(n,S=[])=sigma(n)+sumdiv(n*I,d,if(real(d)&imag(d)&!setsearch(S,d=vecsort(abs([real(d),imag(d)]))),S=setunion(S,[d]);(d[1]+d[2])<<(d[1]!=d[2]))) - _M. F. Hasler_, Nov 22 2007 %K A078930 nonn %O A078930 1,2 %A A078930 _Vladeta Jovovic_, Jan 11 2003