A207956 Number of nX4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 0 vertically.

9, 81, 281, 989, 3923, 15921, 67007, 286299, 1240603, 5420023, 23828357, 105188575, 465711669, 2065999789, 9177987717, 40811215453, 181593070243, 808383490865, 3599754765767, 16033313059243, 71423194026691, 318200352273815

Offset

1,1

Comments

Column 4 of A207960

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +2*a(n-2) -87*a(n-3) +48*a(n-4) +445*a(n-5) -280*a(n-6) -1175*a(n-7) +613*a(n-8) +1664*a(n-9) -614*a(n-10) -1206*a(n-11) +264*a(n-12) +392*a(n-13) -32*a(n-14) -40*a(n-15) for n>16

Example

Some solutions for n=4
..0..1..1..0....1..0..0..1....1..1..0..0....0..1..0..0....0..0..1..1
..0..0..1..1....0..1..0..0....0..0..1..0....0..1..1..1....0..1..1..0
..0..1..0..0....1..0..0..1....1..1..0..0....0..1..1..1....0..1..1..1
..0..0..1..1....0..1..0..0....0..1..1..0....0..1..1..1....0..0..1..1

Crossrefs

Sequence in context: A208040 A208029 A208160 * A207238 A207496 A208165

Adjacent sequences: A207953 A207954 A207955 * A207957 A207958 A207959

Keyword

nonn

Author

R. H. Hardin, Feb 21 2012

Status

approved