# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a180787 Showing 1-1 of 1 %I A180787 #3 Mar 31 2012 12:35:46 %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, Table of n, a(n) for n=1..250 %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 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE