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 A274752 #4 Jul 04 2016 10:27:22 %S A274752 8,81,610,4967,40242,327123,2661918,21656459,176259458,1434313078, %T A274752 11673115263,94995850464,773101634059,6291606309132,51202379223709, %U A274752 416693699123591,3391131540449104,27597636527429286,224594629125220765 %N A274752 Number of 5Xn 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2. %C A274752 Row 5 of A274749. %H A274752 R. H. Hardin, <a href="/A274752/b274752.txt">Table of n, a(n) for n = 1..210</a> %F A274752 Empirical: a(n) = 2*a(n-1) +55*a(n-2) +38*a(n-3) -614*a(n-4) -600*a(n-5) +2769*a(n-6) +2140*a(n-7) -6482*a(n-8) -2606*a(n-9) +7803*a(n-10) +678*a(n-11) -4266*a(n-12) +304*a(n-13) +924*a(n-14) -72*a(n-15) -72*a(n-16) for n>17 %e A274752 Some solutions for n=4 %e A274752 ..0..1..0..1. .0..1..2..1. .0..1..0..1. .0..1..2..1. .0..1..2..1 %e A274752 ..2..0..1..0. .1..0..1..2. .2..0..2..0. .1..2..1..0. .1..0..1..0 %e A274752 ..0..2..0..2. .0..1..0..1. .1..2..0..2. .0..1..2..1. .0..1..0..1 %e A274752 ..2..1..2..0. .1..0..1..0. .2..0..2..1. .1..0..1..2. .1..0..1..0 %e A274752 ..1..0..1..2. .0..1..0..2. .0..2..0..2. .0..1..2..1. .2..1..0..2 %Y A274752 Cf. A274749. %K A274752 nonn %O A274752 1,1 %A A274752 _R. H. Hardin_, Jul 04 2016