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 A260836 #6 Jun 02 2025 12:11:34 %S A260836 188,288,700,1224,1560,3470,6908,10070,18716,39478,64940,111162, %T A260836 228324,409632,690964,1345662,2532216,4354216,8095220,15462342, %U A260836 27373920,49529004,94027168,170716994,306172260,572849570,1056328308,1900057106 %N A260836 Number of (n+2)X(3+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00000011 or 00010101. %C A260836 Column 3 of A260841 %H A260836 R. H. Hardin, <a href="/A260836/b260836.txt">Table of n, a(n) for n = 1..210</a> %F A260836 Empirical: a(n) = 6*a(n-3) +6*a(n-4) -9*a(n-6) -16*a(n-7) -10*a(n-8) +4*a(n-9) +7*a(n-10) +6*a(n-12) +8*a(n-14) +10*a(n-15) +2*a(n-16) +4*a(n-17) +4*a(n-19) +3*a(n-20) +2*a(n-22) for n>24 %e A260836 Some solutions for n=4 %e A260836 ..1..0..1..0..0....0..0..0..0..0....0..0..0..0..1....1..0..0..0..1 %e A260836 ..0..0..0..0..0....0..0..0..0..0....0..0..0..0..0....1..0..0..1..1 %e A260836 ..1..0..0..0..0....1..1..0..0..1....1..1..0..0..0....0..0..0..0..0 %e A260836 ..0..0..0..1..0....0..0..0..0..0....0..0..0..0..1....0..0..0..0..0 %e A260836 ..0..0..0..1..0....0..0..0..0..0....0..0..0..0..1....1..1..0..0..1 %e A260836 ..1..0..0..0..0....0..0..1..1..0....0..1..0..0..0....1..0..0..0..0 %Y A260836 Cf. A260841 %K A260836 nonn %O A260836 1,1 %A A260836 _R. H. Hardin_, Aug 01 2015