A238720 Number of nX2 0..2 arrays with no element equal to the sum modulo 3 of elements to its left or elements above it

2, 4, 10, 16, 42, 64, 170, 256, 682, 1024, 2730, 4096, 10922, 16384, 43690, 65536, 174762, 262144, 699050, 1048576, 2796202, 4194304, 11184810, 16777216, 44739242, 67108864, 178956970, 268435456, 715827882, 1073741824, 2863311530, 4294967296

Offset

1,1

Comments

Column 2 of A238726

Links

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

Formula

Empirical: a(n) = 5*a(n-2) -4*a(n-4)

Example

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

Crossrefs

Sequence in context: A050871 A348305 A277918 * A264585 A077635 A125754

Adjacent sequences: A238717 A238718 A238719 * A238721 A238722 A238723

Keyword

nonn

Author

R. H. Hardin, Mar 03 2014

Status

approved