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 A207914 #7 Jul 22 2025 20:59:20 %S A207914 9,81,271,1309,5371,23637,101069,438103,1887667,8151773,35161937, %T A207914 151744767,654767065,2825582407,12192964863,52615498559,227045509685, %U A207914 979746980809,4227807834119,18243882203687,78726167982599 %N A207914 Number of nX4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically. %C A207914 Column 4 of A207918 %H A207914 R. H. Hardin, <a href="/A207914/b207914.txt">Table of n, a(n) for n = 1..210</a> %F A207914 Empirical: a(n) = 6*a(n-1) -12*a(n-2) +17*a(n-3) +5*a(n-4) +51*a(n-5) +36*a(n-6) -399*a(n-7) +554*a(n-8) -625*a(n-9) -854*a(n-10) -4016*a(n-11) +210*a(n-12) +9416*a(n-13) +9774*a(n-14) +4886*a(n-15) -6673*a(n-16) -6888*a(n-17) -6416*a(n-18) -2847*a(n-19) -607*a(n-20) +1513*a(n-21) +1902*a(n-22) +1033*a(n-23) +100*a(n-24) -185*a(n-25) -162*a(n-26) -18*a(n-27) +8*a(n-29) %e A207914 Some solutions for n=4 %e A207914 ..1..1..1..1....1..0..0..1....0..0..1..1....0..0..1..0....0..1..1..1 %e A207914 ..1..1..1..1....1..1..1..1....1..0..0..1....1..1..0..0....1..0..0..1 %e A207914 ..1..1..1..1....1..1..1..1....1..1..0..0....1..1..0..0....1..0..0..1 %e A207914 ..1..1..0..0....1..0..0..1....1..1..0..0....0..1..0..0....0..0..1..1 %K A207914 nonn %O A207914 1,1 %A A207914 _R. H. Hardin_ Feb 21 2012