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 A229372 #6 Jul 23 2025 05:41:30 %S A229372 3,8,8,22,38,22,60,184,184,60,164,869,1610,869,164,448,4144,13937, %T A229372 13937,4144,448,1224,19675,122497,222990,122497,19675,1224,3344,93589, %U A229372 1067299,3576912,3576912,1067299,93589,3344,9136,444824,9346997,56939585 %N A229372 T(n,k)=Number of nXk 0..2 arrays avoiding 11 horizontally, 22 vertically and 00 antidiagonally. %C A229372 Table starts %C A229372 ....3......8.......22..........60...........164.............448 %C A229372 ....8.....38......184.........869..........4144...........19675 %C A229372 ...22....184.....1610.......13937........122497.........1067299 %C A229372 ...60....869....13937......222990.......3576912........56939585 %C A229372 ..164...4144...122497.....3576912.....104382552......3043629267 %C A229372 ..448..19675..1067299....56939585....3043629267....162794962814 %C A229372 .1224..93589..9346997...911301584...89084628843...8710922742428 %C A229372 .3344.444824.81633583.14532090528.2599351293506.465220677212678 %H A229372 R. H. Hardin, <a href="/A229372/b229372.txt">Table of n, a(n) for n = 1..364</a> %F A229372 Empirical for column k: %F A229372 k=1: a(n) = 2*a(n-1) +2*a(n-2) %F A229372 k=2: a(n) = 2*a(n-1) +13*a(n-2) +3*a(n-3) -13*a(n-4) +4*a(n-5) %F A229372 k=3: [order 11] %F A229372 k=4: [order 24] for n>25 %F A229372 k=5: [order 50] for n>54 %e A229372 Some solutions for n=3 k=4 %e A229372 ..2..1..2..2....1..2..0..2....0..1..0..0....1..0..2..1....0..1..0..1 %e A229372 ..0..2..1..0....0..1..2..1....1..2..2..2....2..1..0..0....2..1..0..2 %e A229372 ..2..0..1..2....2..1..0..1....0..0..0..1....1..2..1..2....1..2..2..1 %Y A229372 Column 1 is A028859 %K A229372 nonn,tabl %O A229372 1,1 %A A229372 _R. H. Hardin_ Sep 21 2013