A198663 Number of nX2 0..4 arrays with values 0..4 introduced in row major order and each element equal to one or two horizontal and vertical neighbors

1, 3, 13, 65, 401, 2798, 21243, 170477, 1414186, 11959573, 102256003, 879709138, 7594221063, 65683697809, 568711886538, 4926993076641, 42698505718759, 370102007685234, 3208288130917763, 27813084430989669, 241122723310051914

Offset

1,2

Comments

Column 2 of A198669

Links

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

Formula

Empirical: a(n) = 12*a(n-1) -18*a(n-2) -96*a(n-3) -43*a(n-4) +384*a(n-5) +1030*a(n-6) +276*a(n-7) -1609*a(n-8) -3144*a(n-9) -1688*a(n-10) +1080*a(n-11) +1536*a(n-12) +768*a(n-13) -512*a(n-14) for n>16

Example

Some solutions with all values 0 to 4 for n=6
..0..0....0..1....0..1....0..0....0..0....0..0....0..0....0..1....0..0....0..1
..1..2....0..1....0..1....1..1....1..1....1..2....1..1....0..1....1..0....0..1
..1..2....1..1....2..1....2..3....2..2....1..2....2..2....2..3....1..2....2..3
..3..3....2..2....2..2....2..3....3..3....3..0....3..4....2..3....3..2....2..3
..1..1....3..3....3..4....1..4....3..3....3..0....3..4....3..4....3..3....4..2
..4..4....4..4....3..4....1..4....4..4....4..4....4..4....3..4....4..4....4..2

Crossrefs

Sequence in context: A080227 A199143 A002468 * A156181 A260783 A228987

Adjacent sequences: A198660 A198661 A198662 * A198664 A198665 A198666

Keyword

nonn

Author

R. H. Hardin Oct 28 2011

Status

approved