A251213 Number of (n+1)X(2+1) 0..1 arrays with no 2X2 subblock having zero or two 1s

21, 63, 191, 589, 1807, 5569, 17119, 52713, 162143, 499081, 1535535, 4725689, 14541087, 44748169, 137696911, 423732505, 1303909887, 4012461097, 12347225455, 37995389753, 116920467935, 359791896905, 1107162729807, 3406999063641

Offset

1,1

Comments

Column 2 of A251219

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) -12*a(n-3) +4*a(n-5).

Empirical: G.f.: -x*(21-82*x^2+16*x^3+32*x^4) / ( -1+3*x+4*x^2-12*x^3+4*x^5 ). - R. J. Mathar, May 12 2016

Example

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

Crossrefs

Sequence in context: A082060 A025525 A033850 * A170930 A113622 A069215

Adjacent sequences: A251210 A251211 A251212 * A251214 A251215 A251216

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved