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 A207367 #7 Jul 22 2025 20:20:49 %S A207367 25,625,3025,14641,45738,142884,353808,876096,1869192,3988009,7660492, %T A207367 14714896,26130832,46403344,77513748,129481641,205925763,327501409, %U A207367 500255371,764135449,1128442546,1666435684,2391271116,3431382084 %N A207367 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 1 vertically. %C A207367 Column 7 of A207368 %H A207367 R. H. Hardin, <a href="/A207367/b207367.txt">Table of n, a(n) for n = 1..210</a> %F A207367 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 A207367 Some solutions for n=4 %e A207367 ..1..0..1..0..1..0..0....0..0..1..0..0..1..0....0..1..0..0..1..0..1 %e A207367 ..0..1..0..1..0..1..0....1..0..1..0..0..1..0....1..0..1..0..1..0..1 %e A207367 ..0..0..1..0..1..0..0....0..0..1..0..0..1..0....0..1..0..0..1..0..0 %e A207367 ..0..1..0..1..0..1..0....0..0..1..0..0..1..0....0..0..1..0..1..0..1 %K A207367 nonn %O A207367 1,1 %A A207367 _R. H. Hardin_ Feb 17 2012