A238722 Number of nX4 0..2 arrays with no element equal to the sum modulo 3 of elements to its left or elements above it

4, 16, 86, 284, 1506, 4636, 24298, 73300, 381280, 1144292, 5923512, 17767180, 91688754, 275195668, 1417323260, 4257556764, 21898760846, 65830136636, 338306366754, 1017543445164, 5226264297018, 15725498143268, 80738182410936

Offset

1,1

Comments

Column 4 of A238726

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 50*a(n-2) -1020*a(n-4) +11131*a(n-6) -71319*a(n-8) +275531*a(n-10) -629492*a(n-12) +789744*a(n-14) -456320*a(n-16) +76800*a(n-18)

Example

Some solutions for n=5
..2..1..2..1....1..2..2..1....2..1..2..1....2..1..1..2....2..1..1..2
..1..2..1..0....2..1..1..2....1..2..1..0....1..0..0..0....1..0..0..0
..2..1..2..0....2..1..2..1....1..2..2..0....1..2..2..0....2..0..0..0
..1..2..1..2....1..0..0..0....2..1..1..0....2..1..1..0....1..0..2..1
..2..1..1..2....2..0..0..0....2..1..1..2....1..0..2..1....2..0..1..1

Crossrefs

Sequence in context: A298012 A006681 A074876 * A184507 A165964 A300279

Adjacent sequences: A238719 A238720 A238721 * A238723 A238724 A238725

Keyword

nonn

Author

R. H. Hardin, Mar 03 2014

Status

approved