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 A275353 #4 Jul 24 2016 10:05:48 %S A275353 5,54,288,1536,8192,43712,235072,1264832,6809856,36666496,197447168, %T A275353 1063304448,5726352128,30839264512,166086172928,894467665408, %U A275353 4817222467584,25943536156672,139721052861440,752479440667648 %N A275353 Number of 3Xn 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,1) or (-1,-2) and new values introduced in order 0..2. %C A275353 Row 3 of A275352. %H A275353 R. H. Hardin, <a href="/A275353/b275353.txt">Table of n, a(n) for n = 1..210</a> %F A275353 Empirical: a(n) = 6*a(n-1) -2*a(n-2) -8*a(n-3) +20*a(n-4) -44*a(n-5) -160*a(n-6) -180*a(n-7) +152*a(n-8) -880*a(n-9) -928*a(n-10) +848*a(n-11) +816*a(n-12) +2752*a(n-13) +2880*a(n-14) +2560*a(n-15) -2048*a(n-16) -4096*a(n-18) for n>20 %e A275353 Some solutions for n=4 %e A275353 ..0..0..0..0. .0..0..0..0. .0..1..0..1. .0..1..0..1. .0..1..0..1 %e A275353 ..1..2..1..1. .1..0..1..2. .1..0..2..0. .0..0..1..0. .0..2..1..2 %e A275353 ..2..2..2..1. .1..2..2..1. .2..2..0..1. .0..2..2..2. .0..2..2..1 %Y A275353 Cf. A275352. %K A275353 nonn %O A275353 1,1 %A A275353 _R. H. Hardin_, Jul 24 2016