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 A183687 #7 Jul 22 2025 09:09:23 %S A183687 768,8912,91136,986128,10382976,110871040,1174759296,12503757968, %T A183687 132720731392,1411193901024,14988337604480,159306506171280, %U A183687 1692418292451712,17985312835495360,191090003735667584 %N A183687 Number of (n+1)X9 binary arrays with every 2X2 subblock nonsingular. %C A183687 Column 8 of A183688 %H A183687 R. H. Hardin, <a href="/A183687/b183687.txt">Table of n, a(n) for n = 1..200</a> %F A183687 Empirical: a(n)=7*a(n-1)+162*a(n-2)-935*a(n-3)-10301*a(n-4)+50843*a(n-5)+343104*a(n-6)-1473463*a(n-7)-6611678*a(n-8)+24960936*a(n-9)+75737800*a(n-10)-253751744*a(n-11)-503746592*a(n-12)+1513486656*a(n-13)+1775133568*a(n-14)-4833383936*a(n-15)-2525235200*a(n-16)+6285426688*a(n-17) %e A183687 Some solutions for 3X9 %e A183687 ..0..1..1..0..1..1..0..1..0....0..1..1..1..0..1..0..1..0 %e A183687 ..1..1..0..1..0..1..1..0..1....1..1..0..1..1..0..1..0..1 %e A183687 ..0..1..1..1..1..1..0..1..0....0..1..1..1..0..1..1..1..0 %K A183687 nonn %O A183687 1,1 %A A183687 _R. H. Hardin_ Jan 06 2011