A203373 Number of (n+1) X 4 0..1 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

108, 748, 5208, 36300, 253068, 1764360, 12301020, 85762188, 597930552, 4168748268, 29064349260, 202635502632, 1412766774396, 9849754525644, 68672102130648, 478779201937548, 3338029812632076, 23272612897409352

Offset

1,1

Comments

Column 3 of A203378.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) -15*a(n-2) +6*a(n-3).

Empirical g.f.: 4*x*(27 - 56*x + 24*x^2) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Jun 04 2018

Example

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

Crossrefs

Cf. A203378.

Sequence in context: A204276 A202194 A333757 * A292343 A228174 A184201

Adjacent sequences: A203370 A203371 A203372 * A203374 A203375 A203376

Keyword

nonn

Author

R. H. Hardin, Dec 31 2011

Status

approved