A180753 Half the number of nX4 binary arrays with each element equal to at least two neighbors.

0, 2, 2, 9, 21, 70, 207, 658, 2059, 6521, 20602, 65244, 206608, 654594, 2073996, 6571885, 20824917, 65991668, 209121585, 662691890, 2100031249, 6654888151, 21089009696, 66830061534, 211781324846, 671125181554, 2126764718766

Offset: 1

Author

R. H. Hardin Sep 20 2010

Keywords

• nonn

Comments

Column 4 of A180760

Links

• R. H. Hardin, Table of n, a(n) for n=1..99

Formula

Empirical: a(n) = 5*a(n-1) - 6*a(n-2) + a(n-3) + a(n-4) - 9*a(n-5) + 4*a(n-6) + a(n-7) + 28*a(n-8) - 16*a(n-9) - 3*a(n-10) + 2*a(n-11) - 6*a(n-12) + 2*a(n-13) - a(n-14)