A185406 1/7 the number of nX3 0..6 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 150, 5040, 279918, 12205368, 595974240, 27536905674, 1306753756812, 61210525548816, 2885367241303254, 135594323017300224, 6381618680273394960, 300126625465471449282, 14119903429577075460420, 664177642891735878467280

Offset: 1

Author

R. H. Hardin Jan 26 2011

Keywords

• nonn

Comments

Column 3 of A185409

Examples

			Some solutions for 5X3 with a(1,1)=0
..0..0..3....0..0..3....0..0..4....0..0..3....0..0..4....0..0..3....0..0..0
..0..2..3....0..0..3....0..0..4....0..1..3....0..0..4....0..0..3....0..1..0
..0..2..3....6..6..6....2..1..1....6..1..0....1..1..0....2..3..3....6..1..3
..5..2..4....4..4..2....2..1..3....6..3..0....2..1..0....2..0..6....6..6..3
..5..4..4....0..0..2....0..0..3....6..3..3....2..2..0....2..0..6....1..1..3
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=27*a(n-1)+1101*a(n-2)-5388*a(n-3)-99699*a(n-4)+111696*a(n-5)+1303703*a(n-6)+1272279*a(n-7)-3839565*a(n-8)-46276758*a(n-9)[phone]*a(n-10)-201107172*a(n-11)-398097784*a(n-12)-1098237564*a(n-13)[phone]*a(n-14)[phone]*a(n-15)-32033066112*a(n-16)[phone]*a(n-17)[phone]*a(n-18)-357171462144*a(n-19)-773247897216*a(n-20)-848592391680*a(n-21)-825363302400*a(n-22)-1632586752000*a(n-23)