A209807 Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having two distinct values, and new values 0..3 introduced in row major order.

7, 34, 173, 930, 5193, 29782, 173789, 1025274, 6089457, 36315262, 217102757, 1299807138, 7788836985, 46697385574, 280057392749, 1679892321738, 10077743984769, 60460730002126, 362743958401973, 2176391017766514

Offset

1,1

Comments

Column 1 of A209814.

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 7*a(n-2) - 28*a(n-3) - 12*a(n-4).

Empirical g.f.: x*(7 - 22*x - 50*x^2 - 20*x^3) / ((1 + x)*(1 - 6*x)*(1 - 3*x - 2*x^2)). - Colin Barker, Jul 13 2018

Example

Some solutions for n=4:
..0..0....0..0....0..0....0..1....0..0....0..0....0..0....0..1....0..0....0..0
..0..1....0..1....1..1....0..0....0..1....0..1....1..0....1..0....0..1....0..1
..1..0....0..1....0..1....0..1....0..0....0..0....0..1....0..1....0..1....1..1
..0..0....0..0....1..0....1..0....0..1....1..0....1..0....1..0....1..0....0..1
..2..2....0..1....0..0....0..0....1..1....1..0....0..1....0..0....0..1....0..0

Crossrefs

Cf. A209814.

Sequence in context: A055271 A209890 A027209 * A351588 A080048 A177140

Adjacent sequences: A209804 A209805 A209806 * A209808 A209809 A209810

Keyword

nonn

Author

R. H. Hardin, Mar 13 2012

Status

approved