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 A180787 #5 Jun 02 2025 03:05:32
%S A180787 0,1,5,64,400,1914,7589,24902,73134,188315,455127,996083,2098908,
%T A180787 4080930,7790731,13869018,24527424,40768032,67955336,106952861,
%U A180787 169909977,255608028,390623704,566247614,837326375,1175991196,1690928973
%N A180787 Number of distinct solutions of sum{i=1..5}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1.
%C A180787 Column 5 of A180793
%H A180787 R. H. Hardin, <a href="/A180787/b180787.txt">Table of n, a(n) for n=1..250</a>
%e A180787 Solutions for sum of products of 5 1..2 pairs = 1 (mod 3) are
%e A180787 (1*1 + 1*1 + 1*1 + 1*2 + 1*2) (1*1 + 1*1 + 1*2 + 1*2 + 2*2)
%e A180787 (1*1 + 1*2 + 1*2 + 2*2 + 2*2) (1*2 + 1*2 + 1*2 + 1*2 + 1*2)
%e A180787 (1*2 + 1*2 + 2*2 + 2*2 + 2*2)
%K A180787 nonn
%O A180787 1,3
%A A180787 _R. H. Hardin_ Sep 20 2010