A251252 Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock having a single 1 or two 1s on the same edge.

18, 56, 150, 446, 1232, 3602, 10108, 29272, 82854, 238640, 678658, 1948718, 5556204, 15926754, 45474920, 130227048, 372121034, 1065071288, 3044724350, 8711869630, 24910552504, 71264572098, 203799138404, 582977750488, 1667293062110

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 4*a(n-2) - 14*a(n-3) + 3*a(n-4) + 3*a(n-5).

Empirical g.f.: 2*x*(9 + x - 45*x^2 + 12*x^3 + 12*x^4) / (1 - 3*x - 4*x^2 + 14*x^3 - 3*x^4 - 3*x^5). - Colin Barker, Nov 27 2018

Example

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

Crossrefs

Column 2 of A251258.

Sequence in context: A086540 A041634 A044975 * A297946 A298384 A298765

Adjacent sequences: A251249 A251250 A251251 * A251253 A251254 A251255

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved