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

1,2

Comments

Column 3 of A185409

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)+164100009*a(n-10)-201107172*a(n-11)-398097784*a(n-12)-1098237564*a(n-13)+6484304364*a(n-14)+1678354992*a(n-15)-32033066112*a(n-16)+111598281360*a(n-17)+135161638848*a(n-18)-357171462144*a(n-19)-773247897216*a(n-20)-848592391680*a(n-21)-825363302400*a(n-22)-1632586752000*a(n-23)

Example

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

Crossrefs

Sequence in context: A135969 A128963 A293097 * A289309 A337032 A250537

Adjacent sequences: A185403 A185404 A185405 * A185407 A185408 A185409

Keyword

nonn

Author

R. H. Hardin Jan 26 2011

Status

approved