%I #3 Mar 31 2012 12:35:46
%S 0,0,9,112,1004,6404,32890,137528,499641,1579113,4551268,11861187,
%T 29034355,65777365,142805210,291148080,576393509,1082580072,
%U 1993354411,3505999065,6088877416,10148269838,16796812567,26776385524,42563703291
%N Number of distinct solutions of sum{i=1..6}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1
%C Column 6 of A180793
%H R. H. Hardin, <a href="/A180788/b180788.txt">Table of n, a(n) for n=1..183</a>
%e Solutions for sum of products of 6 1..2 pairs = 1 (mod 3) are
%e (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*2) (1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 2*2)
%e (1*1 + 1*1 + 1*1 + 1*2 + 2*2 + 2*2) (1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 1*2)
%e (1*1 + 1*1 + 1*2 + 2*2 + 2*2 + 2*2) (1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2)
%e (1*1 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2) (1*2 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2)
%e (1*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%K nonn
%O 1,3
%A _R. H. Hardin_ Sep 20 2010