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 A228457 #8 Sep 01 2013 18:28:17 %S A228457 5,25,95,295,821,2227,6254,18394,55285,165563,489488,1433536,4188613, %T A228457 12268735,36052642,106118146,312319987,918413167,2698818913, %U A228457 7929048609,23298823959,68477103061,201284983126,591668573686,1739085580405 %N A228457 Number of arrays of maxima of three adjacent elements of some length n+2 0..4 array. %C A228457 Column 4 of A228461 %H A228457 R. H. Hardin, <a href="/A228457/b228457.txt">Table of n, a(n) for n = 1..191</a> %F A228457 Empirical: a(n) = 5*a(n-1) -10*a(n-2) +10*a(n-3) +5*a(n-4) -9*a(n-5) +20*a(n-6) +8*a(n-7) +2*a(n-8) +14*a(n-9) +6*a(n-10) +2*a(n-11) +3*a(n-12) +a(n-13) %e A228457 Some solutions for n=4 %e A228457 ..4....3....2....2....4....3....4....3....4....4....4....3....4....3....1....4 %e A228457 ..4....3....1....2....3....3....2....3....4....1....3....1....0....0....0....3 %e A228457 ..4....1....2....0....3....0....0....0....2....0....1....1....4....2....4....3 %e A228457 ..4....2....4....0....0....3....4....0....0....1....4....0....4....3....4....2 %K A228457 nonn %O A228457 1,1 %A A228457 _R. H. Hardin_ Aug 22 2013