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 A206469 #7 Jul 22 2025 19:28:13 %S A206469 7225,958441,23707161,1693734025,61244865529,3420616959081, %T A206469 144660587865049,7310031634630729,329657818912939449, %U A206469 15990423345433902121,740325481079134598041,35313542504161253544969 %N A206469 Number of (n+1)X6 0..2 arrays with every 2X2 subblock having zero permanent. %C A206469 Column 5 of A206472 %H A206469 R. H. Hardin, <a href="/A206469/b206469.txt">Table of n, a(n) for n = 1..210</a> %F A206469 Empirical: a(n) = 55*a(n-1) +978*a(n-2) -78848*a(n-3) +185192*a(n-4) +32350560*a(n-5) -254580608*a(n-6) -5080783360*a(n-7) +56605956096*a(n-8) +280495972352*a(n-9) -4555145707520*a(n-10) -1650631114752*a(n-11) +144197302616064*a(n-12) -230333727375360*a(n-13) -1370695862845440*a(n-14) +3206175906594816*a(n-15) %e A206469 Some solutions for n=4 %e A206469 ..0..0..2..0..2..2....2..1..2..1..2..2....2..0..2..2..1..0....2..2..0..0..2..1 %e A206469 ..0..0..0..0..0..0....0..0..0..0..0..0....2..0..0..0..0..0....0..0..0..0..0..0 %e A206469 ..0..0..2..0..0..2....2..2..2..1..1..1....0..0..0..0..2..1....2..2..0..2..2..0 %e A206469 ..2..0..1..0..0..0....0..0..0..0..0..0....0..2..0..0..0..0....0..0..0..0..0..0 %e A206469 ..1..0..1..0..0..2....0..2..1..2..1..1....0..2..0..0..0..2....2..1..2..2..1..2 %K A206469 nonn %O A206469 1,1 %A A206469 _R. H. Hardin_ Feb 08 2012