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 A207951 #7 Jul 22 2025 21:02:38 %S A207951 16,256,1232,5929,18172,55696,133812,321489,662256,1364224,2526384, %T A207951 4678569,8011752,13719616,22123992,35676729,54856032,84345856, %U A207951 124764640,184552225,264364100,378691600,527969260,736091161,1002761760,1366041600 %N A207951 Number of 5Xn 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 1 0 and 1 0 1 vertically. %C A207951 Row 5 of A207949 %H A207951 R. H. Hardin, <a href="/A207951/b207951.txt">Table of n, a(n) for n = 1..210</a> %F A207951 Empirical: a(n) = 2*a(n-1) +8*a(n-2) -18*a(n-3) -27*a(n-4) +72*a(n-5) +48*a(n-6) -168*a(n-7) -42*a(n-8) +252*a(n-9) -252*a(n-11) +42*a(n-12) +168*a(n-13) -48*a(n-14) -72*a(n-15) +27*a(n-16) +18*a(n-17) -8*a(n-18) -2*a(n-19) +a(n-20) %e A207951 Some solutions for n=4 %e A207951 ..1..0..1..0....0..0..0..0....1..1..0..1....0..1..0..0....1..1..1..1 %e A207951 ..1..0..1..0....0..0..0..0....0..1..0..1....1..1..0..1....1..1..1..1 %e A207951 ..0..0..0..0....1..0..1..0....0..0..0..0....1..1..1..1....1..1..1..1 %e A207951 ..0..0..0..0....1..1..1..0....1..0..0..0....1..0..1..0....1..1..1..0 %e A207951 ..0..0..0..0....1..1..0..0....1..0..0..0....1..0..1..0....1..0..1..0 %K A207951 nonn %O A207951 1,1 %A A207951 _R. H. Hardin_ Feb 21 2012