A206231 Number of (n+1) X 2 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly two equal edges, and new values 0..3 introduced in row major order.

15, 60, 310, 1640, 8910, 51066, 294546, 1710184, 10051522, 59273370, 350336326, 2076929912, 12328636710, 73241168202, 435453806538, 2590088923960, 15409982499130, 91703551575882, 545793722630878, 3248685323916392

Offset

1,1

Comments

Column 1 of A206238.

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -11*a(n-2) +36*a(n-3) -303*a(n-4) +232*a(n-5) +147*a(n-6) +756*a(n-7) for n>8.

Empirical g.f.: x*(15 - 60*x - 5*x^2 - 720*x^3 + 1585*x^4 + 1366*x^5 + 2793*x^6 - 378*x^7) / ((1 - 4*x)*(1 - x - x^2 - 3*x^3)*(1 - 3*x - 7*x^2 - 63*x^3)). - Colin Barker, Jun 14 2018

Example

Some solutions for n=4:
..0..1....0..0....0..1....0..0....0..0....0..1....0..1....0..0....0..0....0..0
..0..0....0..1....0..0....0..1....1..0....2..1....2..0....1..1....0..1....0..1
..0..1....1..2....0..1....1..0....0..1....3..1....0..0....2..1....1..2....1..2
..1..2....1..1....1..0....0..0....0..0....0..1....3..0....1..0....2..2....1..1
..1..1....0..1....0..0....2..2....0..2....3..3....2..1....0..0....1..1....0..0

Crossrefs

Cf. A206238.

Sequence in context: A005945 A223337 A110755 * A001756 A284096 A022288

Adjacent sequences: A206228 A206229 A206230 * A206232 A206233 A206234

Keyword

nonn

Author

R. H. Hardin, Feb 05 2012

Status

approved