%I #5 Jan 02 2022 17:34:07

%S 0,0,0,1,2,6,8,27,30,59,64,147,128,212,265,380,347,623,512,897,882,

%T 1074,1000,1863,1437,1907,2100,2767,2204,3916,2744,4255,4080,4655,

%U 4783,7374,4922,6686,7059,9691,6869,11610,8000,12011,12697,12396,10648,18978,13031

%N Number of distinct solutions of Sum_{i=1..2}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 2..n-2.

%C Column 2 of A180823.

%H R. H. Hardin, <a href="/A180814/b180814.txt">Table of n, a(n) for n=1..999</a>

%e Solutions for sum of products of 2 2..6 pairs = 0 (mod 8) are

%e (2*2 + 2*2) (2*2 + 2*6) (2*2 + 3*4) (2*2 + 4*5) (2*2 + 6*6) (2*3 + 2*5)

%e (2*3 + 3*6) (2*4 + 2*4) (2*4 + 4*4) (2*4 + 4*6) (2*5 + 5*6) (2*6 + 2*6)

%e (2*6 + 3*4) (2*6 + 4*5) (2*6 + 6*6) (3*3 + 3*5) (3*4 + 3*4) (3*4 + 4*5)

%e (3*4 + 6*6) (3*5 + 5*5) (3*6 + 5*6) (4*4 + 4*4) (4*4 + 4*6) (4*5 + 4*5)

%e (4*5 + 6*6) (4*6 + 4*6) (6*6 + 6*6)

%Y Cf. A180823.

%K nonn

%O 1,5

%A _R. H. Hardin_ Sep 20 2010