A207495 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.

6, 36, 102, 297, 932, 2974, 9723, 32164, 107568, 362291, 1226924, 4170948, 14218841, 48567776, 166128066, 568812225, 1948947544, 6681079858, 22911053867, 78586955264, 269607037796, 925049643523, 3174213970624, 10892652172048

Offset

1,1

Comments

Column 3 of A207500.

Links

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

Formula

Empirical: a(n) = 5*a(n-1) -2*a(n-2) -14*a(n-3) +6*a(n-4) +8*a(n-5) -a(n-6) -a(n-7) for n>8.

Empirical g.f.: x*(6 + 6*x - 66*x^2 - 57*x^3 + 119*x^4 + 72*x^5 - 19*x^6 - 11*x^7) / ((1 - x)*(1 - 2*x - x^2)*(1 - 2*x - 5*x^2 + x^4)). - Colin Barker, Mar 05 2018

Example

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

Crossrefs

Cf. A207500.

Sequence in context: A207070 A207118 A207704 * A207249 A060521 A036141

Adjacent sequences: A207492 A207493 A207494 * A207496 A207497 A207498

Keyword

nonn

Author

R. H. Hardin, Feb 18 2012

Status

approved