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 A260840 #6 Jun 02 2025 12:12:05 %S A260840 2584,2976,6908,13170,16000,37882,80516,119194,231008,526102,890868, %T A260840 1551098,3444912,6540148,11105704,22909488,46468620,81665548, %U A260840 156797736,323324270,597713676,1104974160,2236199980,4307963032,7924411232 %N A260840 Number of (n+2)X(7+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00000011 or 00010101. %C A260840 Column 7 of A260841 %H A260840 R. H. Hardin, <a href="/A260840/b260840.txt">Table of n, a(n) for n = 1..210</a> %e A260840 Some solutions for n=4 %e A260840 ..1..1..0..0..1..0..0..0..0....0..1..0..0..1..0..0..1..0 %e A260840 ..0..1..0..0..0..0..0..1..1....0..1..0..0..1..0..0..0..0 %e A260840 ..0..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0..0 %e A260840 ..0..0..0..0..1..0..0..0..0....0..0..0..0..0..0..0..1..1 %e A260840 ..0..1..0..0..1..0..0..1..0....0..1..0..0..1..0..0..0..0 %e A260840 ..1..0..0..0..0..0..0..0..1....1..1..0..0..1..0..0..0..0 %Y A260840 Cf. A260841 %K A260840 nonn %O A260840 1,1 %A A260840 _R. H. Hardin_, Aug 01 2015