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 A181207 #6 Mar 26 2018 09:54:57 %S A181207 8,25,119,484,2117,9025,38936,167281,720083,3097600,13329209,57350329, %T A181207 246768392,1061782225,4568619071,19657722436,84582794333,363940725625, %U A181207 1565955363224,6737954403049,28991906279867,124745667481600 %N A181207 Number of n X 3 binary matrices with no two 1's adjacent diagonally or antidiagonally. %C A181207 Column 3 of A181212. %H A181207 R. H. Hardin, <a href="/A181207/b181207.txt">Table of n, a(n) for n=1..400</a> %F A181207 Empirical: a(n) = 5*a(n-1) - 15*a(n-3) + 9*a(n-4). %F A181207 Empirical g.f.: x*(8 - 15*x - 6*x^2 + 9*x^3) / ((1 - 5*x + 3*x^2)*(1 - 3*x^2)). - _Colin Barker_, Mar 26 2018 %Y A181207 Cf. A181212. %K A181207 nonn %O A181207 1,1 %A A181207 _R. H. Hardin_, Oct 10 2010