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 A268637 #4 Feb 09 2016 12:22:18 %S A268637 240,7128,163878,3440052,68710116,1328460312,25093766490,465757993812, %T A268637 8527096170390,154406753980596,2770879234068744,49351916066147196, %U A268637 873425626212657504,15373652306609086368,269322517606253198046 %N A268637 Number of nX6 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two exactly once. %C A268637 Column 6 of A268639. %H A268637 R. H. Hardin, <a href="/A268637/b268637.txt">Table of n, a(n) for n = 1..210</a> %F A268637 Empirical: a(n) = 60*a(n-1) -1482*a(n-2) +20016*a(n-3) -167163*a(n-4) +924894*a(n-5) -3537110*a(n-6) +9593166*a(n-7) -18693789*a(n-8) +26218062*a(n-9) -26188161*a(n-10) +18139608*a(n-11) -8262712*a(n-12) +2220864*a(n-13) -266256*a(n-14) for n>15 %e A268637 Some solutions for n=3 %e A268637 ..0..0..1..2..2..2. .0..1..2..1..0..0. .1..1..0..0..0..1. .0..1..2..1..0..0 %e A268637 ..0..1..2..2..2..2. .1..2..1..2..1..1. .0..0..0..0..0..0. .0..0..1..2..1..0 %e A268637 ..1..0..2..2..2..1. .2..1..2..1..0..0. .0..0..0..1..0..0. .1..1..2..1..0..1 %Y A268637 Cf. A268639. %K A268637 nonn %O A268637 1,1 %A A268637 _R. H. Hardin_, Feb 09 2016