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 A268976 #4 Feb 16 2016 13:57:16 %S A268976 729,39936,808704,16061328,305242992,5712070032,105294777120, %T A268976 1919046772584,34636116041280,620025612531912,11021514910554528, %U A268976 194739838779510504,3422967847878219552,59892951348957375576 %N A268976 Number of 6Xn 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. %C A268976 Row 6 of A268971. %H A268976 R. H. Hardin, <a href="/A268976/b268976.txt">Table of n, a(n) for n = 1..210</a> %F A268976 Empirical: a(n) = 60*a(n-1) -1466*a(n-2) +19056*a(n-3) -143515*a(n-4) +608478*a(n-5) -957350*a(n-6) -3924114*a(n-7) +27201539*a(n-8) -68079378*a(n-9) +46537423*a(n-10) +212613240*a(n-11) -785654632*a(n-12) +1389943104*a(n-13) -1544105168*a(n-14) +1125401088*a(n-15) -524553472*a(n-16) +142135296*a(n-17) -17040384*a(n-18) for n>26 %e A268976 Some solutions for n=2 %e A268976 ..2..1. .2..2. .0..1. .1..1. .0..0. .2..2. .2..0. .0..1. .0..0. .2..2 %e A268976 ..2..1. .1..2. .2..1. .2..1. .1..0. .1..0. .0..1. .0..0. .0..1. .2..1 %e A268976 ..0..0. .2..1. .2..1. .0..1. .0..1. .0..1. .2..2. .1..0. .2..0. .0..1 %e A268976 ..1..2. .1..2. .2..2. .0..1. .1..0. .0..1. .1..0. .1..0. .1..0. .0..0 %e A268976 ..1..1. .2..1. .0..1. .2..2. .0..0. .2..1. .1..2. .1..0. .0..0. .0..0 %e A268976 ..0..0. .0..1. .0..1. .1..0. .1..0. .2..1. .1..2. .0..1. .1..2. .1..0 %Y A268976 Cf. A268971. %K A268976 nonn %O A268976 1,1 %A A268976 _R. H. Hardin_, Feb 16 2016