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 A275347 #5 Jul 24 2016 10:00:55 %S A275347 5,81,288,1024,4100,16956,70272,291320,1211092,5070832,21255328, %T A275347 89170864,374453028,1574982464,6627474512,27898519192,117476409700, %U A275347 494869331248,2084962994672,8785404327328,37022705828932,156033713723616 %N A275347 Number of nX3 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 A275347 Column 3 of A275352. %H A275347 R. H. Hardin, <a href="/A275347/b275347.txt">Table of n, a(n) for n = 1..210</a> %F A275347 Empirical: a(n) = 4*a(n-1) +12*a(n-2) -48*a(n-3) +66*a(n-4) -210*a(n-5) -1120*a(n-6) +4028*a(n-7) -93*a(n-8) -4098*a(n-9) +27840*a(n-10) -78748*a(n-11) -37816*a(n-12) +204592*a(n-13) -97088*a(n-14) -576*a(n-15) +25984*a(n-16) -12544*a(n-17) for n>20 %e A275347 Some solutions for n=4 %e A275347 ..0..1..2. .0..0..0. .0..1..1. .0..1..0. .0..1..0. .0..1..2. .0..1..0 %e A275347 ..1..1..1. .1..0..2. .1..2..2. .0..2..1. .1..0..1. .2..0..1. .1..2..1 %e A275347 ..0..1..2. .1..2..2. .2..2..2. .2..1..2. .2..2..2. .0..1..0. .2..1..2 %e A275347 ..0..2..2. .2..0..2. .1..0..0. .1..2..1. .1..0..1. .1..0..2. .0..0..1 %Y A275347 Cf. A275352. %K A275347 nonn %O A275347 1,1 %A A275347 _R. H. Hardin_, Jul 24 2016