A268996 Number of 2 X n binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.

4, 13, 35, 103, 278, 763, 2037, 5421, 14264, 37321, 97015, 250963, 646250, 1657719, 4237481, 10798553, 27442092, 69563653, 175938699, 444060607, 1118668286, 2813233523, 7063416349, 17708464645, 44335423456, 110857865665, 276863340767

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - 4*a(n-3) - 11*a(n-4) - 6*a(n-5) - a(n-6).

Empirical g.f.: x*(4 + 5*x - 11*x^2 - 16*x^3 - 7*x^4 - x^5) / ((1 + x)^2*(1 - 2*x - x^2)^2). - Colin Barker, Jan 18 2019

Example

Some solutions for n=4:
..1..0..0..0. .1..0..0..0. .1..1..0..0. .1..0..0..0. .1..0..1..0
..0..0..1..1. .1..0..0..1. .0..0..0..1. .1..0..1..1. .0..0..0..1

Crossrefs

Row 2 of A268995.

Sequence in context: A317781 A271358 A306349 * A270988 A272556 A173723

Adjacent sequences: A268993 A268994 A268995 * A268997 A268998 A268999

Keyword

nonn

Author

R. H. Hardin, Feb 17 2016

Status

approved