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 A183603 #7 Jul 22 2025 09:08:20 %S A183603 6,27,27,120,204,120,534,1479,1479,534,2376,10797,17174,10797,2376, %T A183603 10572,78729,201770,201770,78729,10572,47040,574185,2366412,3831324, %U A183603 2366412,574185,47040,209304,4187499,27768032,72592860,72592860,27768032,4187499 %N A183603 T(n,k)=1/6 the number of (n+1)X(k+1) 0..2 arrays with every 2X2 subblock containing all three values. %C A183603 Table starts %C A183603 .......6.........27..........120.............534..............2376 %C A183603 ......27........204.........1479...........10797.............78729 %C A183603 .....120.......1479........17174..........201770...........2366412 %C A183603 .....534......10797.......201770.........3831324..........72592860 %C A183603 ....2376......78729......2366412........72592860........2220901926 %C A183603 ...10572.....574185.....27768032......1376627608.......68026656422 %C A183603 ...47040....4187499....325834456.....26108240340.....2083981368760 %C A183603 ..209304...30539367...3823553752....495215814566....63854542807704 %C A183603 ..931296..222722937..44868561272...9393691937690..1956721189681174 %C A183603 .4143792.1624313781.526526214848.178194216929170.59964037003007332 %H A183603 R. H. Hardin, <a href="/A183603/b183603.txt">Table of n, a(n) for n = 1..179</a> %e A183603 Some solutions with a(1,1)=0 for 4X3 %e A183603 ..0..1..0....0..0..1....0..2..0....0..1..1....0..1..0....0..1..0....0..0..0 %e A183603 ..2..2..0....1..2..1....0..1..0....2..0..2....2..2..1....1..2..1....1..2..1 %e A183603 ..1..0..1....2..0..2....1..2..0....1..1..2....1..0..2....0..2..0....1..0..0 %e A183603 ..2..2..1....1..1..0....0..2..1....2..0..1....2..2..1....2..1..1....0..2..1 %Y A183603 Column 1 is 3*A021001(n-1) %K A183603 nonn,tabl %O A183603 1,1 %A A183603 _R. H. Hardin_ Jan 05 2011