A274891 Number of nX4 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2.

4, 36, 37, 104, 275, 753, 2049, 5602, 15305, 41866, 114475, 313122, 856462, 2342559, 6407780, 17526908, 47941766, 131135884, 358697083, 981151642, 2683758871, 7340930445, 20079778989, 54924550811, 150236085835, 410943350656

Offset: 1

Author

R. H. Hardin, Jul 10 2016

Keywords

• nonn

Comments

Column 4 of A274895.

Examples

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

Links

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

Crossrefs

Cf. A274895.

Formula

Empirical: a(n) = a(n-1) +8*a(n-2) -28*a(n-4) -9*a(n-5) +55*a(n-6) +16*a(n-7) -70*a(n-8) -9*a(n-9) +56*a(n-10) -28*a(n-12) +a(n-13) +8*a(n-14) -a(n-16) for n>18