cp's OEIS Frontend

A180773 Number of distinct solutions of Sum_{i=1..2} (x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.

%I A180773 #6 Apr 19 2025 10:36:43
%S A180773 0,1,2,6,13,23,36,62,78,123,150,238,255,355,427,567,580,864,810,1202,
%T A180773 1232,1471,1452,2310,1960,2479,2712,3414,2947,4649,3600,5126,5022,
%U A180773 5673,5845,8457,6165,7975,8405,11062,8410,13133,9702,13726,14475,14323,12696
%N A180773 Number of distinct solutions of Sum_{i=1..2} (x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.
%H A180773 R. H. Hardin, <a href="/A180773/b180773.txt">Table of n, a(n) for n=1..999</a>
%e A180773 Solutions for sum of products of 2 1..5 pairs = 0 (mod 6) are
%e A180773 (1*1 + 1*5) (1*2 + 1*4) (1*2 + 2*2) (1*2 + 2*5) (1*2 + 4*4) (1*3 + 1*3)
%e A180773 (1*3 + 3*3) (1*3 + 3*5) (1*4 + 2*4) (1*4 + 4*5) (1*5 + 5*5) (2*2 + 2*4)
%e A180773 (2*2 + 4*5) (2*3 + 2*3) (2*3 + 3*4) (2*4 + 2*5) (2*4 + 4*4) (2*5 + 4*5)
%e A180773 (3*3 + 3*3) (3*3 + 3*5) (3*4 + 3*4) (3*5 + 3*5) (4*4 + 4*5)
%Y A180773 Column 2 of A180782.
%K A180773 nonn
%O A180773 1,3
%A A180773 _R. H. Hardin_, Sep 20 2010