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 A207351 #7 Jul 22 2025 20:19:47 %S A207351 42,1764,8928,43260,186002,684324,2367656,8000806,26057006,82907430, %T A207351 260627110,806084422,2476671718,7545089216,22861190904,68993933764, %U A207351 207422313718,622180142516,1862113694818,5564560256320,16608301418960 %N A207351 Number of 7Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 0 and 1 1 1 vertically. %C A207351 Row 7 of A207346 %H A207351 R. H. Hardin, <a href="/A207351/b207351.txt">Table of n, a(n) for n = 1..210</a> %e A207351 Some solutions for n=4 %e A207351 ..0..1..0..1....0..1..0..0....1..0..1..0....0..1..0..0....1..1..1..1 %e A207351 ..1..0..0..1....0..1..0..1....0..0..1..0....0..1..0..1....1..1..0..1 %e A207351 ..0..0..1..0....1..0..1..0....1..1..0..1....1..0..1..0....0..0..1..0 %e A207351 ..1..1..1..0....1..0..0..1....1..0..1..0....1..1..1..0....1..1..1..1 %e A207351 ..1..0..0..1....0..1..0..1....0..1..0..0....0..1..0..1....0..1..0..1 %e A207351 ..0..1..0..1....1..0..1..0....1..0..0..1....1..0..0..1....0..0..1..0 %e A207351 ..0..0..1..0....1..1..0..1....1..0..1..0....0..0..1..0....1..1..1..0 %K A207351 nonn %O A207351 1,1 %A A207351 _R. H. Hardin_ Feb 17 2012