A242544 Number of length n+3 0..3 arrays with no four elements in a row with pattern aabb (possibly a=b) and new values 0..3 introduced in 0..3 order.

13, 42, 150, 554, 2072, 7808, 29536, 111878, 423969, 1607058, 6092367, 23097242, 87566957, 331989206, 1258663594, 4771951574, 18091832688, 68591328768, 260049450816, 985922294306, 3737915147525, 14171512153838, 53728281674119

Offset: 1

Author

R. H. Hardin, May 17 2014

Keywords

• nonn

Comments

Column 3 of A242549

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -3*a(n-2) +10*a(n-3) -2*a(n-4) -12*a(n-5) -9*a(n-6) -18*a(n-7) -9*a(n-8).

Empirical: G.f.: -x*(-13+10*x-21*x^2+50*x^3+88*x^4+78*x^5+99*x^6+42*x^7) / ( (x^2+x-1)*(3*x^2+3*x-1)*(3*x^2+1)*(x^2+1) ). - R. J. Mathar, May 18 2014