A260921 - OEIS

%I #7 Dec 29 2018 08:06:22

%S 48,68,146,279,468,831,1528,2750,4874,8781,15768,28326,50656,91181,

%T 163232,293511,525366,945120,1691614,3042584,5446082,9796167,17533998,

%U 31538640,56451580,101540858,181748282,326914782,585147672,1052518323

%N Number of (n+2) X (2+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00101011 or 01010101.

%H R. H. Hardin, <a href="/A260921/b260921.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-2) + 6*a(n-4) + 4*a(n-6) - a(n-8) for n>10.

%F Empirical g.f.: x*(48 + 68*x + 98*x^2 + 211*x^3 + 34*x^4 + 144*x^5 - 8*x^6 - 27*x^7 + 2*x^8 - 3*x^9) / ((1 + x + 2*x^3 - x^4)*(1 - x - 2*x^3 - x^4)). - _Colin Barker_, Dec 29 2018

%e Some solutions for n=4:

%e ..0..1..0..1....0..0..1..0....1..0..1..0....0..1..0..0....1..0..0..1

%e ..0..0..1..0....1..0..0..1....0..1..0..0....1..0..1..0....1..0..1..0

%e ..0..1..0..0....1..0..1..0....1..0..1..0....0..1..0..1....0..1..0..1

%e ..1..0..1..0....0..1..0..1....0..1..0..1....1..0..0..0....0..0..1..0

%e ..0..1..0..1....0..0..1..0....1..0..0..0....0..1..0..1....0..1..0..0

%e ..1..0..0..1....1..1..0..0....0..1..0..0....1..0..1..0....1..0..1..0

%Y Column 2 of A260927.

%K nonn

%O 1,1

%A _R. H. Hardin_, Aug 04 2015