This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A180775 #5 Jun 02 2025 03:04:31
%S A180775 0,1,3,34,145,522,1518,4041,9150,19970,38555,74370,128040,224434,
%T A180775 358988,587014,876114,1372578,1941624,2912816,4001868,5742391,7599933,
%U A180775 10831065,13788935,18946564,24080514,32270596,39619720,53256875,63655605,83580675
%N A180775 Number of distinct solutions of sum{i=1..4}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.
%C A180775 Column 4 of A180782
%H A180775 R. H. Hardin, <a href="/A180775/b180775.txt">Table of n, a(n) for n=1..380</a>
%e A180775 Solutions for sum of products of 4 1..3 pairs = 0 (mod 4) are
%e A180775 (1*1 + 1*1 + 1*1 + 1*1) (1*1 + 1*1 + 1*1 + 3*3) (1*1 + 1*1 + 1*2 + 2*2)
%e A180775 (1*1 + 1*1 + 1*3 + 1*3) (1*1 + 1*1 + 2*2 + 2*3) (1*1 + 1*1 + 3*3 + 3*3)
%e A180775 (1*1 + 1*2 + 1*2 + 1*3) (1*1 + 1*2 + 1*3 + 2*3) (1*1 + 1*2 + 2*2 + 3*3)
%e A180775 (1*1 + 1*3 + 1*3 + 3*3) (1*1 + 1*3 + 2*2 + 2*2) (1*1 + 1*3 + 2*3 + 2*3)
%e A180775 (1*1 + 2*2 + 2*3 + 3*3) (1*1 + 3*3 + 3*3 + 3*3) (1*2 + 1*2 + 1*2 + 1*2)
%e A180775 (1*2 + 1*2 + 1*2 + 2*3) (1*2 + 1*2 + 1*3 + 3*3) (1*2 + 1*2 + 2*2 + 2*2)
%e A180775 (1*2 + 1*2 + 2*3 + 2*3) (1*2 + 1*3 + 1*3 + 2*2) (1*2 + 1*3 + 2*3 + 3*3)
%e A180775 (1*2 + 2*2 + 2*2 + 2*3) (1*2 + 2*2 + 3*3 + 3*3) (1*2 + 2*3 + 2*3 + 2*3)
%e A180775 (1*3 + 1*3 + 1*3 + 1*3) (1*3 + 1*3 + 2*2 + 2*3) (1*3 + 1*3 + 3*3 + 3*3)
%e A180775 (1*3 + 2*2 + 2*2 + 3*3) (1*3 + 2*3 + 2*3 + 3*3) (2*2 + 2*2 + 2*2 + 2*2)
%e A180775 (2*2 + 2*2 + 2*3 + 2*3) (2*2 + 2*3 + 3*3 + 3*3) (2*3 + 2*3 + 2*3 + 2*3)
%e A180775 (3*3 + 3*3 + 3*3 + 3*3)
%K A180775 nonn
%O A180775 1,3
%A A180775 _R. H. Hardin_ Sep 20 2010