A181246 Number of n X 3 binary matrices with no 2 X 2 block having four 1's.

8, 57, 417, 3032, 22077, 160697, 1169792, 8515337, 61986457, 451223152, 3284626797, 23910060017, 174050512312, 1266980540057, 9222838063377, 67136581219272, 488712965249117, 3557529413370537, 25896623226618032

Offset

1,1

Comments

Column 3 of A181253.

Links

R. H. Hardin, Table of n, a(n) for n=1..200

Formula

Empirical: a(n) = 6*a(n-1) + 10*a(n-2) - 5*a(n-3).

Empirical g.f.: x*(8 + 9*x - 5*x^2) / (1 - 6*x - 10*x^2 + 5*x^3). - Colin Barker, Mar 26 2018

Crossrefs

Cf. A181253.

Sequence in context: A022038 A277671 A015453 * A281355 A281912 A343352

Adjacent sequences: A181243 A181244 A181245 * A181247 A181248 A181249

Keyword

nonn

Author

R. H. Hardin, Oct 10 2010

Status

approved