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 A228734 #12 Sep 02 2013 13:02:00 %S A228734 3,9,27,77,185,447,1071,2593,6333,15513,38039,93213,228279,558849, %T A228734 1367945,3348489,8196847,20065943,49122291,120253773,294386457, %U A228734 720668887,1764221329,4318870217,10572732933,25882394413,63360952825,155109705901 %N A228734 Number of arrays of the median of three adjacent elements of some length n+2 0..2 array. %H A228734 R. H. Hardin, <a href="/A228734/b228734.txt">Table of n, a(n) for n = 1..210</a> %F A228734 Empirical: a(n) = 3*a(n-1) -a(n-2) -2*a(n-3) +a(n-4) +5*a(n-5) -2*a(n-6) +a(n-7) +a(n-9) +a(n-10) -2*a(n-12) -a(n-13) +a(n-14) %e A228734 Some solutions for n=4 %e A228734 ..1..1..2..0..1..2..1..0..2..1..0..2..0..0..0..1 %e A228734 ..2..2..1..2..2..1..0..2..2..2..0..1..2..2..1..0 %e A228734 ..1..0..2..0..1..2..0..1..1..1..0..0..2..1..0..1 %e A228734 ..1..0..0..0..2..2..0..1..1..0..2..1..1..2..0..2 %Y A228734 Column 2 of A228740. %K A228734 nonn %O A228734 1,1 %A A228734 _R. H. Hardin_ Sep 01 2013