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 A208198 #7 Jul 22 2025 21:14:24 %S A208198 51,41272,39725054,38372808893,37069738362057,35810971705853725, %T A208198 34594950233928279876,33420220819293699707599, %U A208198 32285381308444124871905667,31189077171790298063795540459,30129999876244591484571731949842 %N A208198 Number of nX5 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or left-upward diagonal neighbors. %C A208198 Column 5 of A208201 %H A208198 R. H. Hardin, <a href="/A208198/b208198.txt">Table of n, a(n) for n = 1..210</a> %F A208198 Empirical: a(n) = 928*a(n-1) +38247*a(n-2) -1419908*a(n-3) -25003347*a(n-4) +1012531896*a(n-5) -9450054156*a(n-6) +24082844974*a(n-7) +80821917709*a(n-8) -489140400628*a(n-9) +403243304428*a(n-10) +1648713698424*a(n-11) -3331507779798*a(n-12) +632406681414*a(n-13) +2327643475767*a(n-14) -977046212844*a(n-15) -462110735853*a(n-16) +172474098336*a(n-17) +29511981612*a(n-18) -7270112880*a(n-19) for n>20 %e A208198 Some solutions for n=4 %e A208198 ..0..0..0..1..0....0..0..0..0..0....0..1..0..0..0....0..1..1..0..0 %e A208198 ..0..1..1..0..2....0..1..0..2..0....1..0..0..1..0....0..2..0..0..2 %e A208198 ..2..1..2..2..2....1..0..2..0..1....1..0..2..3..1....1..1..3..1..0 %e A208198 ..0..1..3..1..3....2..1..3..0..0....3..2..2..1..1....0..1..0..2..3 %K A208198 nonn %O A208198 1,1 %A A208198 _R. H. Hardin_ Feb 24 2012