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 A213466 #9 Jun 02 2025 08:02:00 %S A213466 14,310,5542,94238,1568984,25829770,422335348,6874493982,111547175144, %T A213466 1805837931800,29183975631910,471002809679314,7593394526409992, %U A213466 122312334606560252,1968761313647420552,31670562474748858142 %N A213466 Number of 0..3 arrays of length 2*n+1 with sum less than 3*n in any length 2n subsequence (=less than 50% duty cycle). %C A213466 Row 2 of A213464 %H A213466 R. H. Hardin, <a href="/A213466/b213466.txt">Table of n, a(n) for n = 1..210</a> %e A213466 Some solutions for n=3 %e A213466 ..3....0....3....0....2....0....1....0....1....1....3....0....0....2....1....1 %e A213466 ..1....0....1....0....1....0....2....2....2....1....1....0....3....3....1....0 %e A213466 ..1....0....0....2....0....1....0....3....1....1....0....1....3....0....2....2 %e A213466 ..0....3....0....1....0....1....2....0....0....2....1....1....1....0....0....1 %e A213466 ..0....1....1....1....3....1....2....1....2....3....0....1....1....2....1....0 %e A213466 ..3....0....0....2....1....1....0....0....0....0....1....0....0....1....0....1 %e A213466 ..0....3....2....2....1....0....2....1....0....1....1....1....0....1....3....0 %K A213466 nonn %O A213466 1,1 %A A213466 _R. H. Hardin_ Jun 12 2012