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 A266102 #4 Dec 21 2015 08:21:25 %S A266102 1,5,13,36,100,233,680,2201,6508,18689,55362,167587,511996,1565487, %T A266102 4772336,14577149,44758492,137803612,424402090,1307283605,4029557464, %U A266102 12430685471,38368732042,118459868528,365782453416,1129647978659 %N A266102 Number of 2Xn integer arrays with each element equal to the number of horizontal and antidiagonal neighbors exactly one smaller than itself. %C A266102 Row 2 of A266101. %H A266102 R. H. Hardin, <a href="/A266102/b266102.txt">Table of n, a(n) for n = 1..210</a> %F A266102 Empirical: a(n) = 3*a(n-1) -a(n-2) +6*a(n-3) +4*a(n-4) -8*a(n-5) -15*a(n-6) -135*a(n-7) -149*a(n-8) -34*a(n-9) +87*a(n-10) +139*a(n-11) +59*a(n-12) -2*a(n-13) -15*a(n-14) -9*a(n-15) -a(n-16) for n>19 %e A266102 Some solutions for n=4 %e A266102 ..0..1..2..0....1..0..1..1....1..0..0..1....0..0..1..2....0..0..1..1 %e A266102 ..2..1..0..1....1..1..0..1....1..2..1..0....0..1..1..0....1..2..0..0 %Y A266102 Cf. A266101. %K A266102 nonn %O A266102 1,2 %A A266102 _R. H. Hardin_, Dec 21 2015