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 A297852 #13 Feb 20 2018 04:35:46 %S A297852 1,3,7,13,23,49,95,177,359,705,1351,2689,5303,10321,20423,40353,79223, %T A297852 156657,309991,611713,1210967,2399761,4750919,9419937,18694199, %U A297852 37092657,73659175,146373313,290909975,578470225,1150862855,2290191585,4559123447 %N A297852 Number of n X 2 0..1 arrays with every element equal to 1, 2 or 4 king-move adjacent elements, with upper left element zero. %C A297852 Column 2 of A297858. %H A297852 R. H. Hardin, <a href="/A297852/b297852.txt">Table of n, a(n) for n = 1..210</a> %F A297852 Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 4*a(n-3) - 10*a(n-4) + 4*a(n-5) for n>6. %F A297852 Empirical g.f.: x*(1 - 6*x^3 - 4*x^4 + 4*x^5) / ((1 - 2*x)*(1 - x - 4*x^3 + 2*x^4)). - _Colin Barker_, Feb 19 2018 %e A297852 Some solutions for n=7: %e A297852 ..0..1. .0..1. .0..1. .0..0. .0..1. .0..1. .0..0. .0..0. .0..1. .0..0 %e A297852 ..0..1. .1..0. .0..1. .1..0. .0..1. .0..1. .1..1. .1..1. .0..1. .0..1 %e A297852 ..0..1. .1..0. .1..0. .1..1. .0..1. .0..1. .0..1. .1..0. .1..0. .1..1 %e A297852 ..1..0. .0..1. .0..1. .1..1. .1..0. .0..1. .0..0. .0..0. .1..0. .0..0 %e A297852 ..1..0. .0..1. .0..1. .1..0. .1..0. .1..0. .0..0. .0..0. .1..0. .1..1 %e A297852 ..0..1. .0..1. .0..1. .0..0. .0..1. .1..0. .1..0. .0..1. .0..1. .0..1 %e A297852 ..1..0. .1..0. .0..1. .1..1. .0..1. .1..0. .1..1. .1..1. .0..1. .0..0 %Y A297852 Cf. A297858. %K A297852 nonn %O A297852 1,2 %A A297852 _R. H. Hardin_, Jan 07 2018