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 A180794 #6 Jun 02 2025 03:06:08
%S A180794 1,4,8,20,28,56,64,122,150,218,216,424,346,544,667,863,733,1305,1000,
%T A180794 1752,1715,1944,1728,3258,2535,3142,3495,4520,3382,6254,4096,6486,
%U A180794 6243,6812,7315,10959,6868,9400,10121,13922,9271,16388,10648,16520,17805
%N A180794 Number of distinct solutions of sum{i=1..2}(x(2i-1)*x(2i)) = 0 (mod n), with x() in 0..n-1.
%C A180794 Column 2 of A180803
%H A180794 R. H. Hardin, <a href="/A180794/b180794.txt">Table of n, a(n) for n=1..999</a>
%e A180794 Solutions for sum of products of 2 0..4 pairs = 0 (mod 5) are
%e A180794 (0*0 + 0*0) (0*0 + 0*1) (0*0 + 0*2) (0*0 + 0*3) (0*0 + 0*4) (0*1 + 0*1)
%e A180794 (0*1 + 0*2) (0*1 + 0*3) (0*1 + 0*4) (0*2 + 0*2) (0*2 + 0*3) (0*2 + 0*4)
%e A180794 (0*3 + 0*3) (0*3 + 0*4) (0*4 + 0*4) (1*1 + 1*4) (1*1 + 2*2) (1*1 + 3*3)
%e A180794 (1*2 + 1*3) (1*2 + 2*4) (1*3 + 3*4) (1*4 + 2*3) (1*4 + 4*4) (2*2 + 2*3)
%e A180794 (2*2 + 4*4) (2*3 + 3*3) (2*4 + 3*4) (3*3 + 4*4)
%K A180794 nonn
%O A180794 1,2
%A A180794 _R. H. Hardin_, suggested by _Max Alekseyev_ in the Sequence Fans Mailing List, Sep 20 2010