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 A203085 #7 Jul 22 2025 17:00:35 %S A203085 253,787,2237,6615,19723,57699,169561,500813,1473813,4336509,12776787, %T A203085 37624405,110768047,326202095,960592477,2828495527,8329036847, %U A203085 24526561909,72221962493,212669436487,626242809531,1844074518231 %N A203085 Number of (n+2)X4 binary arrays avoiding patterns 000 and 101 in rows and columns. %C A203085 Column 2 of A203091 %H A203085 R. H. Hardin, <a href="/A203085/b203085.txt">Table of n, a(n) for n = 1..210</a> %F A203085 Empirical: a(n) = a(n-1) +2*a(n-2) +10*a(n-3) +6*a(n-4) -5*a(n-5) -10*a(n-6) -8*a(n-7) +2*a(n-8) +10*a(n-9) -24*a(n-10) -20*a(n-11) +23*a(n-12) +22*a(n-13) -10*a(n-14) %e A203085 Some solutions for n=3 %e A203085 ..0..0..1..0....1..0..0..1....0..1..1..0....1..1..1..0....0..0..1..1 %e A203085 ..0..1..1..0....1..1..0..0....1..0..0..1....1..0..0..1....0..0..1..1 %e A203085 ..1..1..1..1....1..1..1..0....1..0..0..1....1..0..0..1....1..1..1..1 %e A203085 ..1..0..0..1....1..1..1..1....1..1..1..0....0..1..1..1....0..1..1..1 %e A203085 ..1..0..0..1....1..0..0..1....0..1..1..0....0..0..1..1....0..0..1..0 %K A203085 nonn %O A203085 1,1 %A A203085 _R. H. Hardin_ Dec 29 2011