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 A180780 #5 Jun 02 2025 03:04:59
%S A180780 0,0,22,499,9730,136491,1430727,11783122,78770456,443607864,
%T A180780 2151608155,9218591346,35373572400,123749340262,398005623516,
%U A180780 1192411118090,3344070542568,8869510553867,22304900540593,53635016669434
%N A180780 Number of distinct solutions of sum{i=1..9}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.
%C A180780 Column 9 of A180782
%H A180780 R. H. Hardin, <a href="/A180780/b180780.txt">Table of n, a(n) for n=1..183</a>
%e A180780 Solutions for sum of products of 9 1..2 pairs = 0 (mod 3) are
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2)
%e A180780 (1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2)
%e A180780 (1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2)
%e A180780 (1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2)
%e A180780 (1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2)
%e A180780 (1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180780 (2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%K A180780 nonn
%O A180780 1,3
%A A180780 _R. H. Hardin_ Sep 20 2010