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A180789 Number of distinct solutions of sum{i=1..7}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1.

%I A180789 #5 Jun 02 2025 03:05:42
%S A180789 0,1,15,198,2282,19300,126861,670058,2997685,11539243,39660969,
%T A180789 122371876,348412793,914595808,2264326584,5259342780,11692554312,
%U A180789 24683815072,50403390786,98560661538,187881799209,345060981679,621482071341
%N A180789 Number of distinct solutions of sum{i=1..7}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1.
%C A180789 Column 7 of A180793
%H A180789 R. H. Hardin, <a href="/A180789/b180789.txt">Table of n, a(n) for n=1..183</a>
%e A180789 Solutions for sum of products of 7 1..2 pairs = 1 (mod 3) are
%e A180789 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1)
%e A180789 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2)
%e A180789 (1*1 + 1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2)
%e A180789 (1*1 + 1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2)
%e A180789 (1*1 + 1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2)
%e A180789 (1*1 + 1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2)
%e A180789 (1*1 + 1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180789 (1*1 + 1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2)
%e A180789 (1*1 + 1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180789 (1*1 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2)
%e A180789 (1*1 + 1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2)
%e A180789 (1*1 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180789 (1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 1*2 + 2*2)
%e A180789 (1*2 + 1*2 + 1*2 + 2*2 + 2*2 + 2*2 + 2*2)
%e A180789 (2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2)
%K A180789 nonn
%O A180789 1,3
%A A180789 _R. H. Hardin_ Sep 20 2010