A242579 Number of length n+3 0..3 arrays with no four elements in a row with pattern aabb (with a!=b) and new values 0..3 introduced in 0..3 order.

14, 45, 159, 587, 2209, 8391, 32020, 122439, 468605, 1794215, 6871124, 26316013, 100792856, 386053397, 1478661408, 5663590035, 21692801897, 83088294355, 318246913929, 1218957694705, 4668884168508, 17882884906745, 68495504779439

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 18*a(n-2) + 32*a(n-3) - 45*a(n-4) + 37*a(n-5) - 21*a(n-6) + 9*a(n-7).

Empirical g.f.: x*(14 - 53*x + 96*x^2 - 164*x^3 + 152*x^4 - 87*x^5 + 45*x^6) / ((1 - x)*(1 - 2*x + x^2 - x^3)*(1 - 4*x + 3*x^2 - 9*x^3)). - Colin Barker, Nov 01 2018

Example

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

Crossrefs

Column 3 of A242584.

Sequence in context: A232855 A232791 A243384 * A206208 A328245 A039368

Adjacent sequences: A242576 A242577 A242578 * A242580 A242581 A242582

Keyword

nonn

Author

R. H. Hardin, May 17 2014

Status

approved