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 A180778 #5 Jun 02 2025 03:04:48
%S A180778 0,0,9,198,2294,19467,126864,674922,2997717,11615754,39660995,
%T A180778 123162204,348412638,920581314,2264397902,5294830516,11692554408,
%U A180778 24858751383,50403391227,99282023930,187902783369,347689331443,621482071507
%N A180778 Number of distinct solutions of sum{i=1..7}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.
%C A180778 Column 7 of A180782
%H A180778 R. H. Hardin, <a href="/A180778/b180778.txt">Table of n, a(n) for n=1..183</a>
%e A180778 Solutions for sum of products of 7 1..2 pairs = 0 (mod 3) are
%e A180778 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2)
%e A180778 (1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 2*2)
%e A180778 (1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 2*2 + 2*2)
%e A180778 (1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2)
%e A180778 (1*1 + 1*1 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2)
%e A180778 (1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2)
%e A180778 (1*1 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180778 (1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2)
%e A180778 (1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%K A180778 nonn
%O A180778 1,3
%A A180778 _R. H. Hardin_ Sep 20 2010