A183359 One quarter the number of nX7 1..4 arrays with no two neighbors of any element equal to each other

972, 36864, 34992, 63504, 137088, 331776, 829440, 1806336, 3852288, 8294400, 18137088, 40144896, 88897536, 196448256, 433465344, 955551744, 2106667008, 4645785600, 10246588416, 22600912896, 49849804800, 109947949056

Offset

1,1

Comments

Column 7 of A183362

Links

R. H. Hardin, Table of n, a(n) for n = 1..58

Formula

Empirical: a(n)=2*a(n-1)+a(n-3)-2*a(n-4)+4*a(n-5)+a(n-6)-a(n-9) for n>14

Example

Some solutions for 5X7 with a(1,1)=1
..1..1..2..3..1..2..2....1..1..3..4..2..1..1....1..2..3..4..1..1..3
..2..4..4..3..1..4..4....2..4..3..1..2..4..3....3..2..1..4..3..2..2
..2..3..1..2..2..3..3....3..4..2..1..3..4..2....3..4..1..2..3..4..4
..4..3..1..4..4..1..1....3..1..2..4..3..1..2....2..4..3..2..1..1..3
..4..2..2..3..3..2..2....2..1..3..4..2..1..4....1..1..3..4..4..2..2

Crossrefs

Sequence in context: A206089 A217162 A203375 * A203030 A209045 A209017

Adjacent sequences: A183356 A183357 A183358 * A183360 A183361 A183362

Keyword

nonn

Author

R. H. Hardin Jan 04 2011

Status

approved