A274799 Number of n X 4 0..2 arrays with no element equal to any value at offset (-1,-2) (-2,-1) (0,-1) or (-1,0) and new values introduced in order 0..2.

4, 22, 112, 596, 3104, 16328, 85504, 448656, 2352080, 12335680, 64684112, 339207984, 1778768656, 9327806784, 48914391648, 256504556080, 1345094908224, 7053603314896, 36988695973168, 193966647764784, 1017150172662336

Offset: 1

Author

R. H. Hardin, Jul 07 2016

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A274803.

Formula

Empirical: a(n) = 2*a(n-1) + 15*a(n-2) + 11*a(n-3) - 2*a(n-4) - 2*a(n-5).

Empirical g.f.: 2*x*(2 + 7*x + 4*x^2 - x^3 - x^4) / (1 - 2*x - 15*x^2 - 11*x^3 + 2*x^4 + 2*x^5). - Colin Barker, Jan 31 2019