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 A185564 #7 Jul 22 2025 09:54:59 %S A185564 1024,3037500,8977824540,26533211918040,78416544382742160, %T A185564 231753101877188629380,684925618712729136913980, %U A185564 2024236566241727245692157080,5982450596328307878990974438640 %N A185564 1/4 the number of nX6 0..3 arrays with no element equal both to the element above and to the element to its left. %C A185564 Column 6 of A185567 %H A185564 R. H. Hardin, <a href="/A185564/b185564.txt">Table of n, a(n) for n = 1..200</a> %F A185564 Empirical: a(n)=3176*a(n-1)-673550*a(n-2)+65136330*a(n-3)-3727689126*a(n-4)+139845804688*a(n-5)-3603160371660*a(n-6)+64834978133874*a(n-7)-810096692648238*a(n-8)+6824155175157060*a(n-9)-36345608355460626*a(n-10)+107463532615201134*a(n-11)-134880780658290660*a(n-12)+77768725332170250*a(n-13)-12154766339477250*a(n-14)-11593534218480000*a(n-15)+6932136333037500*a(n-16)-1023032228765625*a(n-17) %e A185564 Some solutions for 3X6 with a(1,1)=0 %e A185564 ..0..0..0..2..2..2....0..0..0..2..0..0....0..0..0..0..0..3....0..0..0..2..2..3 %e A185564 ..0..2..2..0..1..0....0..2..0..2..2..1....0..2..2..2..0..2....0..2..0..2..0..3 %e A185564 ..0..0..2..2..2..2....0..0..2..3..0..0....0..0..0..2..3..2....0..0..2..3..1..3 %K A185564 nonn %O A185564 1,1 %A A185564 _R. H. Hardin_ Jan 31 2011