A183519 Number of nX2 0..2 arrays with each element equal to either the sum mod 3 of its horizontal and vertical neighbors or the sum mod 3 of its diagonal and antidiagonal neighbors

3, 9, 31, 95, 309, 911, 2803, 8673, 26619, 81959, 252477, 777327, 2393627, 7371657, 22698115, 69895583, 215235669, 662786215, 2040959827, 6284869089, 19353386043, 59596135287, 183518286189, 565119695167, 1740209766219, 5358741068409

Offset

1,1

Comments

Column 2 of A183526

Links

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

Formula

Empirical: a(n)=3*a(n-1)+6*a(n-3)-16*a(n-4)+7*a(n-6)-25*a(n-7)-44*a(n-9)+102*a(n-10)-184*a(n-12)+520*a(n-13)+320*a(n-15)-720*a(n-16)+640*a(n-18)-1600*a(n-19)

Example

Some solutions for 3X2
..1..2....0..2....2..1....2..0....0..2....2..2....1..0....1..0....0..1....1..2
..0..1....1..2....1..2....0..2....1..2....0..0....1..2....1..2....2..1....2..1
..1..2....2..1....0..2....0..0....0..2....1..1....1..0....2..1....1..2....2..0

Crossrefs

Sequence in context: A306526 A034550 A018370 * A001672 A138281 A049416

Adjacent sequences: A183516 A183517 A183518 * A183520 A183521 A183522

Keyword

nonn

Author

R. H. Hardin Jan 05 2011

Status

approved