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 A229637 #8 Apr 27 2021 22:20:40 %S A229637 0,0,0,1,6,0,3,40,39,0,12,122,244,202,0,40,488,1109,1496,925,0,120, %T A229637 1608,6031,10227,8800,3924,0,336,5392,28448,77620,89331,50084,15795,0, %U A229637 896,17368,136778,535671,960325,747299,277996,61182,0,2304,55232,633328 %N A229637 T(n,k) = number of defective 3-colorings of an n X k 0..2 array connected horizontally, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order. %C A229637 Table starts %C A229637 .0.....0.......1........3.........12..........40...........120............336 %C A229637 .0.....6......40......122........488........1608..........5392..........17368 %C A229637 .0....39.....244.....1109.......6031.......28448........136778.........633328 %C A229637 .0...202....1496....10227......77620......535671.......3723370.......25022190 %C A229637 .0...925....8800....89331.....960325.....9722206......98015235......960209886 %C A229637 .0..3924...50084...747299...11485716...170405645....2495874984....35693194243 %C A229637 .0.15795..277996..6049298..133784624..2902520386...61836040854..1290897457785 %C A229637 .0.61182.1513104.47723226.1525870912.48303362606.1498317588826.45634751291449 %H A229637 R. H. Hardin, <a href="/A229637/b229637.txt">Table of n, a(n) for n = 1..287</a> %F A229637 Empirical for column k: %F A229637 k=1: a(n) = a(n-1) %F A229637 k=2: a(n) = 9*a(n-1) - 27*a(n-2) + 27*a(n-3) for n > 5 %F A229637 k=3: a(n) = 15*a(n-1) - 81*a(n-2) + 185*a(n-3) - 162*a(n-4) + 60*a(n-5) - 8*a(n-6) for n > 7. %F A229637 k=4: [order 6] for n > 9. %F A229637 k=5: [order 18] for n > 20. %F A229637 k=6: [order 27] for n > 30. %F A229637 k=7: [order 57] for n > 60. %F A229637 Empirical for row n: %F A229637 n=1: a(n) = 6*a(n-1) - 12*a(n-2) + 8*a(n-3) for n > 6. %F A229637 n=2: a(n) = 6*a(n-1) - 6*a(n-2) - 16*a(n-3) + 12*a(n-4) + 24*a(n-5) + 8*a(n-6). %F A229637 n=3: [order 9] for n > 12. %F A229637 n=4: [order 18] for n > 21. %F A229637 n=5: [order 30] for n > 33. %F A229637 n=6: [order 69] for n > 72. %e A229637 Some solutions for n=3, k=4: %e A229637 0 1 0 2 0 1 0 1 0 1 0 2 0 1 0 0 0 1 1 2 %e A229637 2 1 0 2 2 1 0 1 2 2 0 1 0 2 1 2 0 1 0 2 %e A229637 2 1 2 0 1 2 0 1 1 1 0 1 0 2 1 0 0 1 0 1 %Y A229637 Column 2 is A229600. %Y A229637 Row 1 is A052482(n-2). %K A229637 nonn,tabl %O A229637 1,5 %A A229637 _R. H. Hardin_, Sep 27 2013