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 A274898 #4 Jul 10 2016 20:03:32 %S A274898 24,50,192,753,3017,12217,49697,202749,828828,3391310,13878192, %T A274898 56789705,232384474,950977585,3891812709,15927107508,65180736176, %U A274898 266747574843,1091648042865,4467513170474,18283077346563,74822562153129 %N A274898 Number of 6Xn 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2. %C A274898 Row 6 of A274895. %H A274898 R. H. Hardin, <a href="/A274898/b274898.txt">Table of n, a(n) for n = 1..210</a> %F A274898 Empirical: a(n) = 13*a(n-1) -77*a(n-2) +286*a(n-3) -736*a(n-4) +1351*a(n-5) -1787*a(n-6) +1716*a(n-7) -1217*a(n-8) +652*a(n-9) -265*a(n-10) +78*a(n-11) -14*a(n-12) +a(n-13) for n>14 %e A274898 Some solutions for n=4 %e A274898 ..0..1..2..1. .0..1..0..2. .0..1..2..0. .0..1..2..0. .0..1..0..2 %e A274898 ..0..2..0..1. .2..1..0..2. .0..1..2..1. .0..1..2..1. .2..1..0..1 %e A274898 ..1..2..1..2. .1..0..2..1. .1..2..0..1. .1..2..0..1. .1..0..2..1 %e A274898 ..2..0..1..2. .1..0..1..0. .1..2..0..2. .1..2..1..2. .1..2..1..0 %e A274898 ..0..1..2..0. .0..2..1..0. .2..0..1..2. .2..0..1..2. .0..2..1..0 %e A274898 ..0..1..2..0. .2..1..0..2. .2..0..2..0. .2..0..2..0. .0..1..0..2 %Y A274898 Cf. A274895. %K A274898 nonn %O A274898 1,1 %A A274898 _R. H. Hardin_, Jul 10 2016