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 A207392 #7 Jul 22 2025 20:21:47 %S A207392 6,36,98,271,834,2307,6115,16544,44250,116526,307117,808976,2122787, %T A207392 5564987,14588870,38216326,100064540,261992129,685862456,1795255303, %U A207392 4698927663,12298716264,32188880680,84245176534,220486127041 %N A207392 Number of 3Xn 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 1 0 vertically. %C A207392 Row 3 of A207391 %H A207392 R. H. Hardin, <a href="/A207392/b207392.txt">Table of n, a(n) for n = 1..210</a> %F A207392 Empirical: a(n) = 3*a(n-1) -2*a(n-2) +9*a(n-3) -15*a(n-4) -21*a(n-6) +16*a(n-7) +11*a(n-8) +27*a(n-9) +2*a(n-10) -12*a(n-12) -a(n-13) -2*a(n-14) +2*a(n-15) %e A207392 Some solutions for n=4 %e A207392 ..1..0..0..0....1..1..1..1....1..1..1..1....0..0..0..0....0..0..0..0 %e A207392 ..1..0..1..1....0..0..0..0....1..1..1..1....0..1..1..1....0..1..1..0 %e A207392 ..1..0..1..1....0..1..1..1....1..1..1..1....0..1..1..0....0..1..1..0 %K A207392 nonn %O A207392 1,1 %A A207392 _R. H. Hardin_ Feb 17 2012