A205312 - OEIS

A205312

Number of (n+1) X 3 0..1 arrays with every 2 X 2 subblock having the same number of equal edges, and new values 0..1 introduced in row major order.

20, 84, 376, 1708, 7784, 35500, 161928, 738636, 3369320, 15369324, 70107976, 319801228, 1458790184, 6654348460, 30354161928, 138462112716, 631602239720, 2881086973164, 13142230386376, 59948977985548, 273460429154984

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Column 2 of A205318.

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) -7*a(n-2) +2*a(n-3).

Empirical g.f.: 4*x*(5 - 9*x + 3*x^2) / ((1 - x)*(1 - 5*x + 2*x^2)). - Colin Barker, Jun 11 2018

EXAMPLE

Some solutions for n=4:

..0..0..0....0..1..0....0..0..1....0..1..1....0..0..1....0..1..0....0..0..1

..0..0..0....0..1..0....0..1..1....1..1..0....0..1..1....0..0..0....0..1..1

..0..0..0....0..1..1....1..1..0....1..0..0....0..0..1....1..0..1....0..1..0

..0..0..0....1..1..0....0..1..0....1..1..1....0..1..1....0..0..1....0..0..0

..0..0..0....1..0..0....0..0..0....0..0..1....1..1..0....0..1..1....1..0..1

CROSSREFS

Cf. A205318.

Sequence in context: A044588 A172221 A006566 * A268888 A211158 A154077

Adjacent sequences: A205309 A205310 A205311 * A205313 A205314 A205315

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 25 2012

STATUS

approved