A242317 Number of length n+2+2 0..2 arrays with every value 0..2 appearing at least once in every consecutive 2+3 elements, and new values 0..2 introduced in order.

25, 61, 145, 337, 781, 1829, 4269, 9957, 23233, 54225, 126533, 295265, 689021, 1607877, 3752057, 8755625, 20431737, 47678569, 111260509, 259632437, 605866385, 1413822053, 3299230409, 7698933081, 17965877829, 41924350093, 97832744293

Offset: 1

Author

R. H. Hardin, May 10 2014

Keywords

• nonn

Comments

Column 2 of A242322.

Examples

			Some solutions for n=5:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....1....1....1....0....1....0....0....1....1....1
..0....2....1....2....1....0....2....1....0....1....0....1....1....0....1....2
..1....2....2....0....2....1....2....2....0....2....2....1....0....2....0....0
..2....0....0....1....0....2....2....2....2....2....2....2....2....1....2....1
..1....2....2....0....2....0....0....0....1....0....1....2....2....2....1....2
..1....1....1....2....2....1....1....1....0....1....2....0....2....0....2....1
..0....1....2....2....1....1....1....0....0....2....0....1....1....2....0....2
..0....0....2....0....2....0....2....0....1....2....2....0....0....0....2....0
		

Links

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

Crossrefs

Cf. A242322.

Formula

Empirical: a(n) = a(n-1) + 2*a(n-2) + 2*a(n-3) + 2*a(n-4) - a(n-5) - a(n-6).

Empirical g.f.: x*(25 + 36*x + 34*x^2 + 20*x^3 - 18*x^4 - 13*x^5) / ((1 + x)*(1 - 2*x - 2*x^3 + x^5)). - Colin Barker, Mar 19 2018