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 A229538 #8 Apr 27 2021 21:17:13 %S A229538 0,324,2038,24344,221096,2171944,19965136,184319130,1664588696, %T A229538 14941791994,132720725536,1171588072850,10275058180372,89663150159240, %U A229538 778803031279908,6737980364090108,58088493991210808,499217935061929964 %N A229538 Number of defective 3-colorings of a 5 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order. %C A229538 Row 5 of A229534. %H A229538 R. H. Hardin, <a href="/A229538/b229538.txt">Table of n, a(n) for n = 1..210</a> %F A229538 Empirical: a(n) = 12*a(n-1) + 26*a(n-2) - 566*a(n-3) - 123*a(n-4) + 8804*a(n-5) - 4121*a(n-6) - 59620*a(n-7) + 55115*a(n-8) + 183692*a(n-9) - 256127*a(n-10) - 211910*a(n-11) + 498819*a(n-12) - 48036*a(n-13) - 371692*a(n-14) + 214008*a(n-15) + 43848*a(n-16) - 64656*a(n-17) + 8640*a(n-18) + 5184*a(n-19) - 1296*a(n-20) for n > 22. %e A229538 Some solutions for n=4: %e A229538 0 1 2 2 0 1 2 1 0 1 0 2 0 1 2 0 0 1 2 1 %e A229538 0 1 0 1 2 1 0 2 2 1 0 1 2 1 2 0 2 1 0 1 %e A229538 0 2 0 2 0 1 0 2 2 1 2 0 2 1 2 1 2 1 2 1 %e A229538 0 1 0 2 0 1 0 2 2 1 2 1 1 0 2 1 2 1 2 1 %e A229538 0 1 0 1 0 1 0 1 0 1 2 0 2 0 2 1 0 1 0 2 %Y A229538 Cf. A229534. %K A229538 nonn %O A229538 1,2 %A A229538 _R. H. Hardin_, Sep 25 2013