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 A228751 #10 Sep 12 2018 15:08:41 %S A228751 5,50,482,4599,43862,418370,3990739,38067290,363121586,3463797759, %T A228751 33040991486,315176359538,3006451507579,28678390419458, %U A228751 273561730649282,2609491655262279,24891810279661862,237441732282894050 %N A228751 Number of n X 5 binary arrays with top left element equal to 1 and no two ones adjacent horizontally or antidiagonally. %H A228751 R. H. Hardin, <a href="/A228751/b228751.txt">Table of n, a(n) for n = 1..210</a> %F A228751 Empirical: a(n) = 13*a(n-1) - 36*a(n-2) + 29*a(n-3) - 5*a(n-4) for n>5. %F A228751 Empirical g.f.: x*(5 - 15*x + 12*x^2 - 12*x^3 + 2*x^4) / ((1 - x)*(1 - 12*x + 24*x^2 - 5*x^3)). - _Colin Barker_, Sep 12 2018 %e A228751 Some solutions for n=4: %e A228751 ..1..0..1..0..0....1..0..0..0..0....1..0..0..0..0....1..0..0..0..0 %e A228751 ..1..0..1..0..1....0..0..0..0..0....1..0..1..0..0....1..0..0..0..0 %e A228751 ..0..0..1..0..0....1..0..0..0..1....1..0..1..0..0....0..0..0..0..1 %e A228751 ..1..0..0..1..0....0..1..0..0..1....1..0..1..0..0....1..0..0..0..0 %Y A228751 Column 5 of A228754. %K A228751 nonn %O A228751 1,1 %A A228751 _R. H. Hardin_, Sep 02 2013