A241329 Number of 2 X n 0..3 arrays with no element equal to fewer vertical neighbors than horizontal neighbors, with new values 0..3 introduced in row major order.

2, 8, 59, 530, 4877, 45057, 416533, 3851085, 35606121, 329205872, 3043762177, 28141931363, 260193887579, 2405693427789, 22242493569775, 205649030142198, 1901384099152245, 17579764368539693, 162538497819201097

Offset: 1

Author

R. H. Hardin, Apr 19 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 2 of A241328.

Formula

Empirical: a(n) = 12*a(n-1) - 26*a(n-2) + 2*a(n-3) + 28*a(n-4) - 6*a(n-5) - 9*a(n-6) for n>8.

Empirical g.f.: x*(2 - 16*x + 15*x^2 + 26*x^3 - 21*x^4 - 17*x^5 + 5*x^6 + 3*x^7) / ((1 - x)*(1 - x - x^2)*(1 - 10*x + 6*x^2 + 9*x^3)). - Colin Barker, Oct 29 2018